Transmission, control device, and vehicle

ABSTRACT

A transmission for outputting a rotational torque in accordance with a torque requirement. The transmission includes a generator, a motor and a control device. The generator includes a rotor configured to receive first rotational power from an engine, a stator including a stator core with a winding wound thereon, a magnetic circuit for the winding passing through the stator core, and a supply current adjustment device configured to adjust magnetic resistance of the magnetic circuit for the winding, to thereby change an inductance of the winding to adjust a current outputted by the generator. The motor is driven by the current outputted from the generator, to thereby output second rotational power. The control device controls the supply current adjustment device to change the inductance of the winding, in accordance with the torque requirement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part application of International ApplicationPCT/JP2015/082930, filed on Nov. 24, 2015, which is based on, and claimspriority to, Japanese Patent Application No. 2014-237372, filed on Nov.25, 2014, and Japanese Patent Application Nos. 2015-196667, 2015-196668,2015-196669 and 2015-196670, all filed on Oct. 2, 2015, the contents ofwhich are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a transmission, a control device, and avehicle.

BACKGROUND ART

Conventionally known is the following transmission. In the transmission,a rotational output (rotational power) of an engine is converted intoelectric power by a generator. The electric power resulting from theconversion is converted into rotational power by a motor. The rotationalpower resulting from the conversion is supplied to a rotating mechanism.

For example, Japanese Patent Application Laid-Open No. 2002-345109(“JPA'109”) shows a vehicle. The vehicle shown in JPA'109 is a hybridvehicle. This vehicle includes an engine, an accelerator pedal, a firstrotary electric machine, a second rotary electric machine, and a drivewheel. The first rotary electric machine is coupled to an output shaftof the engine. The first rotary electric machine functions mainly as agenerator. The second rotary electric machine is electrically connectedto the first rotary electric machine. The second rotary electric machinefunctions mainly as a motor. A set of the first and second rotaryelectric machines is used as a transmission machine. By a currentflowing in the first rotary electric machine and the second rotaryelectric machine, power running is performed. The second rotary electricmachine is coupled to the drive wheel of the vehicle.

In the vehicle as shown in JPA'109, a depression of the acceleratorpedal depressed by a driver represents a request for acceleration of thevehicle. The vehicle as shown in JPA'109 is, if provided with anelectronic-controlled throttle device, able to optionally adjust theamount of air taken in by the engine. The vehicle is, therefore,controlled in the following manner, for example. A target output of thesecond rotary electric machine (motor) is determined based on thevehicle speed and the amount of depression of the accelerator pedaldepressed by the driver. A target electric power to be generated by thefirst rotary electric machine (generator) is determined in accordancewith the target output of the second rotary electric machine. A targetoutput of the engine is determined in accordance with the targetelectric power to be generated. The amount of air taken in and theamount of fuel injected by the engine are controlled so as to achievethe target output. In this control, the first rotary electric machine iscontrolled in its generating electric power and the second rotaryelectric machine is controlled in its output. In a case where thevehicle as shown in JPA'109 is configured with its accelerator pedalmechanically coupled with its engine throttle, the electric powergenerated by the first rotary electric machine and the output of thesecond rotary electric machine are controlled in accordance with anactual output of the engine. In JPA'109, as described above, electricpower (output) of the rotary electric machine is controlled so as toallow applications to various types of vehicles with differentcharacteristics.

BRIEF SUMMARY OF THE INVENTION

The vehicle as shown in JPA'109 controls the amount of air taken in andthe amount of fuel injected by the engine, in order to control thetorque of the drive wheel. The vehicle as shown in JPA'109 increases theamount of air taken in and the amount of fuel injected by the engine, inorder to increase the torque of the drive wheel. A situation requiringan increase of the torque of the drive wheel occurs in accelerating thevehicle, for example. As the amount of air taken in and the amount offuel injected by the engine increase, the rotation speed of the engineincreases. That is, rotational power outputted from the engineincreases. As a result, a current outputted from the first rotaryelectric machine that functions as a generator increases, so that acurrent supplied to the second rotary electric machine increases. Theincrease of the current supplied to the second rotary electric machinecauses an increase of the torque outputted from the second rotaryelectric machine to the drive wheel. Here, there has been a problem thatthe current outputted from the generator is less readily increased thanthe rotation speed of the generator is.

In the vehicle as shown in JPA'109, therefore, an attempt to increase apower generation current for the purpose of increasing the torqueoutputted from the second rotary electric machine requires an excessiveincrease of the output power of the engine. This may decrease the fuelefficiency. Dealing with the voltage, which increases in response to theincrease of the output power of the engine, may also decrease the fuelefficiency.

The present invention provides a transmission, a control device, and avehicle, capable of enlarging a torque adjustment range with suppressionof a decrease in fuel efficiency of the engine.

In various embodiments, the present invention adopts the followingconfigurations:

(1) A transmission configured to vary a rotational torque and a rotationspeed outputted from an engine and supply the varied rotational torqueand rotation speed to a rotating mechanism,

the transmission comprising:

-   -   a generator that outputs electric power according to rotational        power transmitted from the engine, the generator including a        rotor, a stator, and a supply current adjustment device, the        rotor including a permanent magnet, the rotor rotated by the        rotational power transmitted from the engine, the stator        arranged opposite to the rotor, the stator including a winding        and a stator core with the winding wound thereon, the supply        current adjustment device configured to adjust a current to be        outputted from the generator, the adjustment implemented by        changing an inductance of the winding, the change implemented by        changing a magnetic resistance of a magnetic circuit for the        winding, which passes through the stator core;    -   a motor that is driven by the electric power outputted from the        generator, and outputs rotational power to the rotating        mechanism; and    -   a control device that controls the supply current adjustment        device in accordance with a torque requirement of the        transmission, to direct the supply current adjustment device to        adjust the current to be outputted from the generator by        changing the inductance of the winding, the torque requirement        requesting a torque to be outputted from the transmission to the        rotating mechanism.

In the transmission of (1), the rotor of the generator is rotated by therotational power transmitted from the engine. At this time, a magneticflux of the permanent magnet included in the rotor acts on the winding.This generates an induced voltage. The induced voltage causes electricpower to be outputted. The generator outputs electric power according tothe rotational power transmitted from the engine. The motor is driven bythe electric power outputted from the generator, to output rotationalpower.

In the transmission of (1), the control device controls the supplycurrent adjustment device in accordance with the torque requirement ofthe transmission, the torque requirement requesting a torque to beoutputted to the rotating mechanism. The supply current adjustmentdevice adjusts the current to be outputted from the generator bychanging the inductance of the winding. A rotational torque to beoutputted from the motor to the rotating mechanism is adjustedaccordingly.

In the generator, the magnetic resistance of the magnetic circuit forthe winding, which passes through the stator core, is changed so thatthe inductance is changed. The ratio of a current change to a voltagechange obtained when changing the magnetic resistance of the magneticcircuit for the winding, which passes through the stator core, isdifferent from that obtained when changing the output of the engine.

The control device controls the current of the generator by controllingthe supply current adjustment device in accordance with the torquerequirement requesting a torque to be outputted to the rotatingmechanism. This can suppress an excessive increase of the rotationalpower of the engine. The control device is also able to adjust thetorque to be outputted to the rotating mechanism while ensuring abalance between the voltage and the electric power generated in thegenerator. Accordingly, the transmission of (1) is capable of enlarginga torque adjustment range with suppression of a decrease in fuelefficiency of the engine.

(2) The transmission of (1), further comprising a motor power controldevice provided in an electric power supply path between the generatorand the motor, the motor power control device configured to controlelectric power to be supplied to the motor, wherein

the control device controls both the motor power control device and thesupply current adjustment device.

In the configuration of (2), the control device is able to control theelectric power to be supplied to the motor, independently of controllingthe output of the generator. For example, even while the engine and thegenerator are operating, the motor can be brought into a stopped stateby the motor power control device stopping the supply of the electricpower to the motor. Accordingly, the configuration of (2) provides anincreased degree of freedom in terms of controlling the rotationoutputted from the motor.

(3) The transmission of (1), wherein

the engine includes an output adjustment device that adjusts rotationalpower to be outputted from the engine, and

the control device cooperates with the output adjustment device todirect the supply current adjustment device to adjust the current to beoutputted from the generator by changing the inductance of the winding.

In the configuration of (3), the control device cooperates with theoutput adjustment device to adjust the current to be outputted from thegenerator. Thus, the current to be supplied from the generator to themotor can be adjusted with suppression of an excessive increase of therotational power of the engine. Accordingly, the configuration of (3) isable to adjust the torque with suppression of a decrease in fuelefficiency of the engine.

(4) The transmission of any one of (1) to (3), wherein

the magnetic circuit for the winding, which passes through the statorcore, includes at least one non-magnetic gap, and

the supply current adjustment device adjusts the current to be outputtedfrom the generator, the adjustment implemented by changing theinductance of the winding, the change implemented by changing a magneticresistance of a non-magnetic gap being among the at least onenon-magnetic gap, the non-magnetic gap existing between the winding andthe rotor.

In the configuration of (4), the supply current adjustment devicechanges the inductance of the winding by changing the magneticresistance of the non-magnetic gap existing between the winding and therotor. The permanent magnet moving along with rotation of the rotorcauses an alternating magnetic field to occur between the winding andthe rotor. For example, reducing the magnetic resistance of thenon-magnetic gap existing between the winding and the rotor leads to areduction of an alternating magnetic field loss. This can increase thecurrent relative to the rotational power supplied to the rotor.Accordingly, the current to be outputted from the generator can beadjusted to an increased degree.

(5) The transmission of any one of (1) to (4), wherein

the magnetic circuit for the winding, which passes through the statorcore, includes at least one non-magnetic gap, and

the supply current adjustment device adjusts the current to be outputtedfrom the generator, the adjustment implemented by changing theinductance of the winding, the change implemented by changing a magneticresistance of a non-magnetic gap being among the at least onenon-magnetic gap, the non-magnetic gap whose magnetic resistance beinghighest when the inductance of the winding is set to the highestsettable value.

The configuration of (5) changes the magnetic resistance of thenon-magnetic gap whose magnetic resistance is highest when theinductance of the winding is set to the highest settable value. Thismakes it easy to increase the amount of change of the inductance of thewinding. Accordingly, the current can be adjusted to an increaseddegree.

(6) The transmission of any one of (1) to (5), wherein

the supply current adjustment device adjusts the current to be outputtedfrom the generator, the adjustment implemented by changing theinductance of the winding such that the change rate of a magnetic fluxlinked with the winding is lower than the change rate of the inductanceof the winding, the change implemented by changing the magneticresistance of the magnetic circuit for the winding, which passes throughthe stator core.

In the configuration of (6), the supply current adjustment devicechanges the inductance of the winding such that the change rate of themagnetic flux linked with the winding is lower than the change rate ofthe inductance of the winding. The magnetic flux linked with the windingis influential to the voltage and current. The inductance of the windingis influential mainly to the current. The supply current adjustmentdevice is, therefore, able to adjust the supply current with the changerate of the voltage being lower than the change rate of the current.That is, the supply current adjustment device is able to adjust thecurrent while less influenced by voltage constraints. Accordingly, theconfiguration of (6) is capable of enlarging a torque adjustment rangewith further suppression of a decrease in fuel efficiency of the engine.

(7) The transmission of any one of (1) to (6), wherein

the supply current adjustment device adjusts the current to be outputtedfrom the generator, the adjustment implemented by changing theinductance of the winding, the change implemented by changing themagnetic resistance of the magnetic circuit for the winding, whichpasses through the stator core, the change of the magnetic resistanceimplemented by moving the position of at least a portion of the statorcore relative to the winding.

In the configuration of (7), the supply current adjustment devicechanges the magnetic resistance of the magnetic circuit for the winding,which passes through the stator core, the change implemented by movingthe position of at least a portion of the stator core relative to thewinding. The inductance of the winding can be changed easily. That is,the current to be supplied to the motor is readily adjustable.Accordingly, the torque to be outputted from the motor is readilyadjustable.

(8) The transmission of (7), wherein

the supply current adjustment device adjusts the current to be outputtedfrom the generator, the adjustment implemented by changing theinductance of the winding, the change implemented by changing themagnetic resistance of the magnetic circuit for the winding, whichpasses through the stator core, the change of the magnetic resistanceimplemented by moving the position of the stator core relative to thewinding while maintaining the position of the stator core relative tothe rotor.

The configuration of (8) moves the position of the stator core relativeto the winding while maintaining the position of the stator corerelative to the rotor. This can suppress a change of the magnetic fluxthat flows from the permanent magnet of the rotor to the stator core.That is, a change of the magnetic flux generated by the permanent magnetand linked with the winding is suppressed. As a result, a change of thevoltage is suppressed which otherwise might be caused by movement of theposition of the stator core relative to the winding. Accordingly, theconfiguration of (8) is capable of enlarging a torque adjustment rangewith further suppression of a decrease in fuel efficiency of the engine.

(9) The transmission of any one of (1) to (7), wherein

the supply current adjustment device adjusts the current to be outputtedfrom the generator, the adjustment implemented by changing theinductance of the winding, the change implemented by changing themagnetic resistance of the magnetic circuit for the winding, whichpasses through the stator core, the change of the magnetic resistanceimplemented by moving the winding.

The configuration of (9) moves the position of the winding relative tothe stator core while maintaining the position of the stator corerelative to the rotor. This can suppress a change of the magnetic fluxthat flows from the permanent magnet of the rotor to the stator core.That is, a change of the magnetic flux generated by the permanent magnetand linked with the winding is suppressed. As a result, a change of thevoltage is suppressed which otherwise might be caused by movement of theposition of the stator core relative to the winding. Accordingly, theconfiguration of (9) is capable of enlarging a torque adjustment rangewith further suppression of a decrease in fuel efficiency of the engine.

(10) The transmission of any one of (1) to (4), wherein

the generator includes a supply voltage adjustment device that adjusts avoltage to be outputted from the generator, the adjustment implementedby changing an induced voltage of the winding, the change implemented bychanging a linkage flux flowing from the permanent magnet of the rotorand linked with the winding.

The configuration of (10) is able to adjust the voltage outputted fromthe generator in a way other than by the engine output adjustment deviceadjusting the rotational power. This provides an increased degree offreedom in terms of controlling the rotation, with suppression of adecrease in fuel efficiency of the engine.

(11) The transmission of (10), wherein

the supply voltage adjustment device adjusts the voltage to be outputtedfrom the generator, the adjustment implemented by changing the inducedvoltage of the winding, the change implemented by changing the linkageflux generated from the permanent magnet of the rotor and linked withthe winding, the change of the linkage flux implemented by moving theposition of the permanent magnet relative to the winding.

The configuration of (11) makes it easy to adjust the voltage to beoutputted from the generator. It is therefore easy to provide anincreased degree of freedom in terms of controlling the rotation.

(12) The transmission of any one of (1) to (4), wherein

the stator core includes a plurality of first stator core parts and asecond stator core part, each of the plurality of first stator coreparts having a facing portion that is opposite to the rotor with anon-magnetic gap therebetween, the second stator core part not havingthe facing portion, and

the supply current adjustment device changes the magnetic resistance ofthe magnetic circuit for the winding, which passes through the statorcore, the change implemented by moving one of the plurality of firststator core parts and the second stator core part relative to the other.

In the configuration of (12), the supply current adjustment device movesone of the plurality of first stator core parts and the second statorcore part included in the stator core relative to the other. Such aconfiguration provides a larger change of the magnetic resistance of themagnetic circuit for the winding, which passes through the stator core,as compared with a configuration in which, for example, one of thestator core and a member different from the stator core is movedrelative to the other. Thus, the current to be supplied to the motor canbe adjusted over a wider range in accordance with the torquerequirement. Accordingly, the configuration of (9) is capable of furtherenlarging the torque adjustment range with further suppression of adecrease in fuel efficiency of the engine.

(13) The transmission of (12), wherein

the supply current adjustment device changes the magnetic resistance ofthe magnetic circuit for the winding, which passes through the statorcore, the change implemented by moving one of the plurality of firststator core parts and the second stator core part relative to the otherso as to shift from a first state to a second state,

the first state being a state in which the length of a non-magnetic gapbetween each of the plurality of first stator core parts and the secondstator core part is shorter than the length of a non-magnetic gapbetween adjacent ones of the plurality of first stator core parts,

the second state being a state in which the length of the non-magneticgap between each of the plurality of first stator core parts and thesecond stator core part is longer than the length of the non-magneticgap between adjacent ones of the plurality of first stator core parts.

In the configuration of (13), in the first state, the length of thenon-magnetic gap between each of the plurality of first stator coreparts and the second stator core part is shorter than the length of thenon-magnetic gap between adjacent ones of the plurality of first statorcore parts. In the second state, the length of the non-magnetic gapbetween each of the plurality of first stator core parts and the secondstator core part is longer than the length of the non-magnetic gapbetween adjacent ones of the plurality of first stator core parts.

In the first state, therefore, a portion of the magnetic flux generatedby the current in the winding, which portion flows through thenon-magnetic gap between the adjacent first stator core parts, mostlyflows through the non-magnetic gap between the first stator core partand the second stator core part. That is, the magnetic flux generated bythe current in the winding mostly flows through both the first statorcore parts and the second stator core part. In the second state, themagnetic resistance of the magnetic circuit passing through the firststator core part is higher. A greater change of the magnetic resistanceof the magnetic circuit for the winding, which passes through the statorcore, is obtained. Accordingly, the configuration of (13) is capable offurther enlarging the torque adjustment range with further suppressionof a decrease in fuel efficiency.

(14) A control device for use in the transmission of any one of (1) to(13),

the control device comprising:

-   -   a torque request receiving device configured to receive a torque        request for the transmission, the torque request requesting a        torque to be outputted from the transmission to the rotating        mechanism; and    -   an adjustment control device that controls the supply current        adjustment device configured to adjust the current by changing        the inductance of the winding, in accordance with the torque        request received by the torque request receiving device.

The control device of (14) is capable of enlarging the torque adjustmentrange in the transmission with suppression of a decrease in fuelefficiency of the engine.

(15) A vehicle comprising:

the transmission of any one of (1) to (13);

an engine that supplies rotational power to the transmission; and

a rotational drive mechanism serving as the rotating mechanism, therotational drive mechanism supplied with rotational power to drive thevehicle, the rotational power having a torque and a rotation speedvaried by the transmission.

In the vehicle of (15), the requirement for the torque to be outputtedfrom the transmission varies depending on the status of traveling of thevehicle. If an increase of the torque is required, the transmission isable to respond to the requirement for increasing the torque withsuppression of a decrease in fuel efficiency of the engine. Accordingly,the vehicle of (15) is capable of enlarging a torque adjustment rangewith suppression of a decrease in fuel efficiency of the engine.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention is capable of enlarging a torque adjustment rangewith suppression of a decrease in fuel efficiency of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an outline configuration of anapparatus having mounted thereon a transmission according to a firstembodiment of the present invention.

FIG. 2 is a system configuration diagram showing an outlineconfiguration of the transmission shown in FIG. 1.

FIG. 3A is a schematic diagram for explanation of adjustment made by asupply current adjustment device included in a generator shown in FIG.2; and FIG. 3B is a schematic diagram showing a state in which theinductance of a winding is set lower than that of FIG. 3A.

FIG. 4 is a circuit diagram schematically showing an equivalent circuitof a winding included in the generator shown in FIGS. 3A and 3B.

FIG. 5 is a flowchart of an operation of the transmission.

FIG. 6A is a schematic diagram for explanation of adjustment made by asupply current adjustment device included in a generator of atransmission according to a second embodiment; and FIG. 6B is aschematic diagram showing a state in which the inductance of a windingis set lower than that of FIG. 6A.

FIG. 7 is a schematic diagram showing a generator of a transmissionaccording to a third embodiment.

FIG. 8A is a schematic diagram showing a first state of a stator shownin FIG. 7; and FIG. 8B is a schematic diagram showing a second state ofthe stator shown in FIG. 7.

FIG. 9 is a graph showing output current characteristics relative to therotation speed of a rotor included in the generator shown in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

A description will be given of studies conducted by the present inventorabout a transmission that varies the rotational torque and the rotationspeed of an engine and supplies the varied rotational torque androtation speed to a rotating mechanism.

When, for example, the vehicle as shown in JPA'109 travels at a highspeed, the second rotary electric machine serving as the motor needs torotate at a high speed. This requires a high voltage to be supplied tothe second rotary electric machine. For this purpose, the vehicleincreases the amount of air taken in and the amount of fuel injected bythe engine. In this manner, the vehicle increases the voltage suppliedfrom the first rotary electric machine serving as the generator to thesecond rotary electric machine.

When, for example, the vehicle as shown in JPA'109 travels uphill, thesecond rotary electric machine serving as the motor needs to output ahigh torque. This requires a large current to be supplied to the secondrotary electric machine. For this purpose, the vehicle increases theamount of air taken in and the amount of fuel injected by the engine. Inthis manner, the vehicle increases the voltage outputted from thegenerator. An increase of a power generation voltage causes an increaseof a power generation current of the generator.

The power generation current flows in a winding. The power generationcurrent is impeded by the impedance of the winding. The impedance can beexpressed as the product ωL of the inductance of the winding of thegenerator and the angular velocity of rotation. As the rotation speed ofthe engine increases, the impedance of the winding which impedes thepower generation current increases.

In the vehicle as shown in JPA'109, therefore, an attempt to increasethe power generation current of the generator for the purpose ofincreasing the output torque of the motor results in a greater increaseof the rotational power of the engine as compared with an increase ofthe power generation current. This can increase a loss.

In the vehicle as shown in JPA'109, moreover, an attempt to increase thepower generation current of the generator for the purpose of increasingthe output torque of the motor results in a greater increase of thevoltage of the generator as compared with an increase of the powergeneration current. An electrical component connected thereto needs tohave a high breakdown voltage. An output current of the generator isprecisely controlled by, for example, turning on/off switching elementsthat are arranged between the generator and a motor. The switchingelements having a high breakdown voltage for withstanding the increasedvoltage have a high on-resistance. This leads to a decrease inefficiency due to a heat loss of the switching elements.

Hence, the vehicle shown in JPA'109 causes a decrease in fuelefficiency.

The present inventor made further studies on the above-describedproblems. As a result, the present inventor discovered that the reasonwhy the above-described problems occur in the vehicle as shown inJPA'109 is that the output of the generator is controlled withoutdistinction between the current and voltage so that the current and thevoltage are highly interactive with each other.

For solving the above-described problems, the present inventor furthermade intensive studies.

It has been believed that an increase of a current outputted from agenerator is caused mainly by an increase of a voltage, and this is notunique to the vehicle as shown in JPA'109. A voltage is increased by,for example, an increase of the rotation speed, an increase of amagnetic force, or an increase of the number of turns of a winding. Acurrent reaches saturation as the rotation speed increases due to anarmature reaction. The increase of the magnetic force or the increase ofthe number of turns of the winding leads to a size increase.

One conceivable way to increase the current outputted from the generatoris reducing the armature reaction which is caused by an inductance. Ithowever has been considered that reducing the inductance of a windingleads to reducing a linkage flux, which makes it difficult to increasethe current.

The present inventor focused on a magnetic circuit. A magnetic circuitthat influences the inductance is a magnetic circuit for a winding. Themagnetic circuit for a winding is different from a magnetic circuit thatextends from a magnet of a rotor and passes through a winding. Thestudies conducted by the present inventor were based on cleardistinction between the magnetic circuit for a winding and the magneticcircuit that extends from a magnet of a rotor and passes through awinding. The present inventor consequently discovered that a largechange of the inductance can be implemented by changing the magneticresistance of the magnetic circuit for a winding.

As a consequence, the present inventor obtained the following findings:in a transmission, adjusting a current by changing the inductance of awinding of a generator can reduce interaction between the current andvoltage.

The transmission of the present invention is accomplished based on thefindings above. In the transmission of the present invention, a controldevice controls a supply current adjustment device. The supply currentadjustment device changes the magnetic resistance of a magnetic circuitfor a winding, which passes through a stator core, in accordance with atorque requirement requesting a torque to be outputted to a rotatingmechanism. In this manner, the supply current adjustment device changesthe inductance of the winding, to adjust a current to be supplied to anelectrical load device. The ratio of a current change to a voltagechange obtained when changing the magnetic resistance of the magneticcircuit for the winding, which passes through the stator core, is higherthan that obtained when changing the rotation speed of an engine.Accordingly, the transmission of the present invention is able to adjustthe current to be supplied to a motor with less interaction between thevoltage change and the current change as compared with when, forexample, not changing the inductance. That is, the transmission is ableto adjust the output torque of the transmission with less interactionbetween the voltage change and the current change. The transmission istherefore able to increase the output torque without causing anexcessive increase of rotational power of the engine. The transmissionis also able to increase the output torque of the transmission withoutcausing an excessive increase of the power generation voltage. Thisleads to an improvement in the fuel efficiency of the engine. Also, anexcessive increase of the voltage is suppressed. This allows adoption ofa switching element having a low breakdown voltage. The switchingelement with a low breakdown voltage has a low resistance when it is ON.A heat loss is suppressed, and therefore a high efficiency can beobtained. Accordingly, a fuel efficiency of the engine is improved.

As described above, the transmission of the present invention is capableof enlarging a torque adjustment range with suppression of a decrease infuel efficiency of the engine. In addition, the transmission of thepresent invention is compatible to both an engine with a wide rotationspeed range and an engine with a narrow rotation speed range.

In the following, the present invention will be described based onpreferred embodiments and with reference to the drawings.

First Embodiment

FIG. 1 is a block diagram showing an outline configuration of anapparatus having mounted thereon a transmission T according to a firstembodiment of the present invention.

FIG. 1 shows a vehicle V as an example of the apparatus having mountedthereon the transmission T. The vehicle V includes the transmission Tand a vehicle body D. The vehicle body D of the vehicle V includes anengine 14, wheels Wa, Wb, Wc, Wd, a requirement indication device A, andan engine control device EC.

The transmission T is connected to drive wheels Wc, Wd among the wheelsWa to Wd. The drive wheels Wc, Wd are connected to the transmission Tvia a transmission mechanism G. The engine 14 and the transmission Tdrive the drive wheels Wc, Wd in rotation so that the vehicle V travels.

The drive wheels Wc, Wd represent one example of the rotational drivemechanism of the vehicle according to the present invention. Therotational drive mechanism represents one example of the rotatingmechanism of the present invention.

The engine 14 is an internal combustion engine. The engine 14 causesfuel combustion. Thus, the engine 14 outputs mechanical power. Theengine 14 includes an output shaft C. The output shaft C is, forexample, a crankshaft.

As for power transmission from the engine 14 to the drive wheels Wc, Wd,the engine 14 is not connected to the drive wheels Wc, Wd by anymechanical component.

The engine 14 does not directly drive the drive wheels Wc, Wd by therotational power of the engine 14. Therefore, the control of therotational power of the engine 14 is less influenced by constraintsinherent in operation characteristics of the drive wheels Wc, Wd. Thisprovides a high degree of freedom in terms of controlling the rotationalpower of the engine 14.

The engine 14 includes an engine output adjustment device 141. Theengine output adjustment device 141 adjusts the rotational power of theengine 14. The engine output adjustment device 141 includes a throttlevalve adjustment mechanism and a fuel injection device (not shown). Thethrottle valve adjustment mechanism adjusts the amount of air taken inby the engine 14. The fuel injection device supplies a fuel to theengine 14. The engine output adjustment device 141 controls the amountof air taken in and the amount of fuel injected by the engine 14. Inthis manner, the engine output adjustment device 141 adjusts therotational power outputted from the engine 14. For example, the engineoutput adjustment device 141 increases the amount of air taken in andthe amount of fuel injected by the engine 14. This causes an increase ofthe rotational power of the engine 14. As the rotational power of theengine 14 increases, the rotation speed of the output shaft C increases.The rotation speed of the output shaft C represents the rotation speedof the engine 14.

The engine control device EC controls the engine output adjustmentdevice 141. The engine output adjustment device 141 adjusts therotational power of the engine 14 under control of the engine controldevice EC.

The transmission T is a mechanism that transmits rotational poweroutputted from the engine 14 to the drive wheels Wc, Wd serving as therotating mechanism. The transmission T receives a supply of rotationalpower, and outputs the rotational power.

The transmission T is mechanically connected to the engine 14 via theoutput shaft C of the engine 14 such that rotational power istransmitted from the engine 14 to the transmission T. The transmission Tis mechanically connected to the drive wheels Wc, Wd via thetransmission mechanism G such that rotational power is transmitted tothe drive wheels Wc, Wd. The transmission T includes a generator 10, acontrol device 15, a converter 16, an inverter 17, and a motor 18. Thetransmission T varies the rotational torque and the rotation speedoutputted from the engine 14, and supplies the varied ones to the drivewheels Wc, Wd. Details of the transmission T will be given later.

The request indication device A outputs a torque requirement. Therequest indication device A has an accelerator operator.

More specifically, the request indication device A is operated by adriver of the vehicle V. The request indication device A outputs arequest for acceleration of the vehicle V based on the operation and thestatus of traveling of the vehicle V. The request for acceleration ofthe vehicle V corresponds to a requirement of a torque outputted fromthe transmission T. The output of the vehicle V corresponds to an outputof the motor 18. The request for acceleration of the vehicle Vcorresponds to a request for an output torque of the motor 18. Theoutput torque of the motor 18 corresponds to a current supplied to themotor 18. Therefore, the output torque of the motor 18 corresponds to acurrent outputted from the generator 10.

The request indication device A outputs a torque request as anacceleration request, the torque request requesting a torque outputtedfrom the transmission T.

The torque request requesting a torque outputted from the transmission Tcorresponds to a current request requesting a current supplied from thegenerator 10 to the motor 18.

In this embodiment, the request indication device A outputs the torquerequest and a speed request. For example, in a situation mainlyrequiring acceleration of the vehicle, an increase of the torque to beoutputted to the drive wheels Wc, Wd is required. For example, in asituation mainly requiring an increase of the traveling speed of thevehicle, an increase of the rotation speed to be outputted to the drivewheels Wc, Wd is required.

The request indication device A is connected to the engine controldevice EC and the transmission T. To be specific, the request indicationdevice A outputs a signal representing the request to the engine controldevice EC and the transmission T. The engine control device EC and thetransmission T cooperate with each other.

Here, it may be possible that the request indication device A isconnected to the transmission T via the engine control device EC. Insuch a configuration, the transmission T receives the torque request viathe engine control device EC.

[Transmission]

FIG. 2 is a system configuration diagram showing an outlineconfiguration of the transmission T shown in FIG. 1.

The transmission T includes the generator 10, the control device 15, theconverter 16, the inverter 17, and the motor 18.

The generator 10 receives rotational power from the engine 14, andsupplies a current to the motor 18.

As for power transmission from the engine 14 to the generator 10, thegenerator 10 is mechanically connected to the engine 14. The generator10 is connected to the output shaft C of the engine 14. The generator 10is directly connected to the output shaft C. For example, the generator10 may be attached to a crank case (not shown) of the engine 14.Alternatively, for example, the generator 10 may be arranged in aposition distant from the crank case (not shown).

The generator 10 includes a rotor 11, a stator 12, and a supply currentadjustment device 131.

The generator 10 is a three-phase brushless generator. The rotor 11 andthe stator 12 constitute a three-phase brushless generator.

The rotor 11 includes permanent magnets. To be more specific, the rotor11 includes a plurality of magnetic pole parts 111 and a back yoke part112. The magnetic pole part 111 is made of a permanent magnet. The backyoke part 112 is made of, for example, a ferromagnetic material. Themagnetic pole parts 111 are arranged between the back yoke part 112 andthe stator 12. The magnetic pole parts 111 are attached to the back yokepart 112. The plurality of magnetic pole parts 111 are arranged so as toalign in a circumferential direction Z about the rotation axis of therotor 11, that is, so as to align in the direction of rotation of therotor 11. The plurality of magnetic pole parts 111 are arranged suchthat N-poles and S-poles alternate with respect to the circumferentialdirection Z. The generator 10 is a three-phase brushless generator ofpermanent magnet type. A winding for supplying a current is not providedon the rotor 11.

The stator 12 is arranged opposite to the rotor 11. The stator 12includes a plurality of windings 121 and a stator core 122. The statorcore 122 is made of, for example, a ferromagnetic material. The statorcore 122 forms a magnetic circuit of the stator 12. The plurality ofwindings 121 are wound on the stator core 122. The stator core 122includes a core main body 122 a (see FIGS. 3A and 3B) and a plurality ofteeth 122 b. The core main body 122 a functions as a yoke. The pluralityof teeth 122 b extend from the core main body 122 a toward the rotor 11.The plurality of teeth 122 b protrude from the core main body 122 atoward the rotor 11. The teeth 122 b extending toward the rotor 11 havetheir distal end surfaces opposite to the magnetic pole parts 111 of therotor 11 with an air gap therebetween. The teeth 122 b of the statorcore 122 and the magnetic pole parts 111 of the rotor 11 directly faceeach other. The plurality of teeth 122 b, which are arranged atintervals with respect to the circumferential direction Z, align in thecircumferential direction Z. Each of the plurality of windings 121 iswound on each of the plurality of teeth 122 b. Each winding 121 is woundso as to pass through a slot between the plurality of teeth 122 b. Eachwinding 121 corresponds to any of the three phases, namely, U-phase,V-phase, and W-phase. The windings 121 corresponding to U-phase,V-phase, and W-phase are arrange in order in the circumferentialdirection Z.

The rotor 11 is connected to the output shaft C of the engine 14. Therotor 11 is rotated along with rotation of the output shaft C. The rotor11 has the magnetic pole parts 111 rotating in a state where themagnetic pole parts 111 are opposite to the teeth 122 b of the statorcore 122. As the rotor 11 rotates, magnetic fluxes linked with thewindings 121 change. As a result, an induced voltage is generated in thewindings 121. This is how the generator 10 performs power generation.The generator 10 supplies a generated current to the motor 18. Thecurrent outputted from the generator 10 is supplied to the motor 18. Tobe specific, the current outputted from the generator 10 is supplied tothe motor 18 via the converter 16 and the inverter 17. As the currentoutputted from the generator 10 increases, a current supplied from theconverter 16 to the inverter 17 increases, so that a current supplied tothe motor 18 increases. A voltage outputted from the generator 10 issupplied to the motor 18 via the converter 16 and the inverter 17.

In this embodiment, the rotor 11 and the stator 12 have an axial gapstructure. The rotor 11 and the stator 12 are opposite to each otherwith respect to the direction (axial direction) X of the rotation axisof the rotor 11. The plurality of teeth 122 b included in the stator 12protrude in the axial direction X from the core main body 122 a. In thisembodiment, the axial direction X is a direction in which the rotor 11and the stator 12 are opposite to each other.

The supply current adjustment device 131 adjusts the current to besupplied from the generator 10 to the motor 18. For adjusting thecurrent to be supplied to the motor 18, the supply current adjustmentdevice 131 changes the inductance of the winding 121. The supply currentadjustment device 131 changes the magnetic resistance of a magneticcircuit for the winding 121. The magnetic circuit for the winding 121 isa magnetic circuit that passes through the stator core 122. In thismanner, the supply current adjustment device 131 changes the inductanceof the winding 121. The supply current adjustment device 131 is acurrent adjustment mechanism. The magnetic circuit for the winding 121is, for example, a close-loop circuit. The magnetic circuit for thewinding 121 is a circuit that passes through an internal path of thewinding 121, then goes out from one end portion (the end portion closeto the rotor) of the internal path of the winding 121, then enters oneend portion (the end portion close to the rotor) of an internal path ofan adjacent winding 121, then passes through the internal path of theadjacent winding 121, then goes out from the other end portion (the endportion remote from the rotor) of the internal path of the adjacentwinding 121, and then enters the other end portion (the end portionremote from the rotor) of the internal path of the winding 121. Theinternal path of the winding 121 is a path provided within the winding121 so as to extend in the direction in which the rotor 11 and thestator 12 are opposite to each other. The magnetic circuit for thewinding 121 partially has a non-magnetic gap such as an air gap. Themagnetic circuit for the winding is, for example, made up of the statorcore 122 and a non-magnetic gap.

Details of the adjustment of the inductance made by the supply currentadjustment device 131 will be given later.

The converter 16 and the inverter 17 are provided in an electric powersupply path between the generator 10 and the motor 18. The converter 16is connected to the generator 10. The inverter 17 is connected to theconverter 16 and the motor 18. Electric power outputted from thegenerator 10 is supplied through the converter 16 and the inverter 17 tothe motor 18.

The converter 16 rectifies the current outputted from the generator 10.The converter 16 converts a three-phase AC outputted from the generator10 into a DC. The converter 16 outputs the DC. The converter 16 has aninverter circuit, for example. The converter 16 has a three-phase bridgeinverter circuit, for example. The three-phase bridge inverter circuitincludes switching elements Sa corresponding to the respective threephases. On/off operations of the switching elements Sa are controlledbased on a signal supplied from a position sensor (not shown) thatdetects the rotation position of the rotor 11.

The operation of the converter 16 is controlled by the control device15. For example, the converter 16 changes the timing for turning on/offthe switching elements Sa relative to a predetermined phase angle in thethree-phase AC. In this manner, the converter 16 can adjust the currentto be supplied to the motor 18. This is how the converter 16 adjusts theelectric power to be supplied to the motor 18.

The adjustment made by the converter 16 is mainly for limiting thecurrent generated by the generator 10. The adjustment made by theconverter 16 is different from controlling the current by changing theinductance of the generator 10. The following description will be givenunder the assumption that the limiting of the current made by theconverter 16 is minimum.

It is also possible that the converter 16 has a bridge circuit includingdiodes. That is, the converter 16 may be configured as a rectifier. Insuch a case, the converter 16 performs only rectification withoutperforming the control of the current.

The motor 18 is operated by electric power that is supplied from thegenerator 10. The motor 18 drives the drive wheels Wc, Wd in rotation.Thus, the motor 18 makes the vehicle V travel. As for powertransmission, the motor 18 is not mechanically connected to thegenerator 10.

The motor 18 is, for example, a three-phase brushless motor. The motor18 includes a rotor 181 and a stator 182. The rotor 181 and the stator182 of the motor 18 of this embodiment have the same structure as thatof the rotor 11 and the stator 12 of the generator 10.

In the transmission T of this embodiment, the generator 10 iselectrically connected to the motor 18. It is therefore not necessary toarrange a mechanical power transmission between the generator 10 and themotor 18. This provides a high degree of freedom in terms of arrangementof the generator 10 and the motor 18. For example, it is possible thatthe generator 10 is provided in the engine 14 while the motor 18 isarranged near the drive wheels Wc, Wd serving as the rotating mechanism.

The rotor and the stator of the motor 18 may be configured differentlyfrom those of the generator 10. For example, the number of magneticpoles or the number of teeth of the motor 18 may be different from thoseof the generator 10. For example, an induction motor or a stepper motormay be adopted as the motor 18. For example, a DC motor with brushes maybe adopted as the motor 18.

The motor 18 is mechanically connected to the drive wheels Wc, Wd suchthat rotational power is transmitted to the drive wheels Wc, Wd. Themotor 18 is mechanically connected to the drive wheels Wc, Wd via thetransmission mechanism G. More specifically, the rotor 181 of the motor18 is connected to the transmission mechanism G. A portion of the rotor181 connected to the transmission mechanism G functions as a rotationaloutput device of the transmission T.

An output of the motor 18 is an output of the transmission T. A requestfor an output of the transmission T, which means a request for an outputof the motor 18, varies depending on the status of traveling of thevehicle V. For example, a situation is assumed in which a request forgently increasing the traveling speed is issued when the vehicle V istraveling on a flat terrain at a constant speed. In this case, thedegree of acceleration is low, and thus the amount of increase of theoutput torque required of the motor 18 is relatively small. While themotor 18 is rotating at a constant speed, an induced voltage accordingto the rotation speed is generated in the motor 18. The induced voltageis generated so as to impede the current that is supplied to the motor18 for driving the motor 18. Therefore, the current supplied to themotor 18 is relatively small. To respond to the request for gentlyincreasing the traveling speed, an increase of the voltage supplied tothe motor 18 is required.

On the other hand, a situation is assumed in which a sudden accelerationor uphill traveling of the vehicle V is requested. This requires arelatively large amount of increase of the output torque of the motor18. In this case, the amount of increase of the current supplied to themotor 18 needs to be large.

The inverter 17 supplies the current for driving the motor 18 to themotor 18. The inverter 17 is supplied with a DC from the converter 16.The inverter 17 converts the DC outputted from the converter 16 into athree-phase current with phases shifted by 120 degrees. The phases ofthe three-phase current correspond to the three phases of thethree-phase brushless motor, respectively. The inverter 17 has aninverter circuit, for example. The inverter 17 has a three-phase bridgeinverter circuit, for example. The three-phase bridge inverter circuitincludes switching elements Sb each corresponding to each of the threephases. The switching elements Sb are controlled based on a signalsupplied from a position sensor (not shown) that detects the rotationposition of the rotor 181.

The inverter 17 adjusts on/off operations of the switching elements Sb,to control the voltage to be supplied to the motor 18. For example, theinverter 17 turns on the switching elements Sb based on apulse-width-modulated signal. The control device 15 adjusts the dutycycle of ON/OFF. Thus, the voltage to be supplied to the motor 18 iscontrolled to an arbitrary value by the control device 15. This is howthe inverter 17 adjusts the electric power to be supplied to the motor18.

Each of the inverter 17 and the converter 16 represents one example ofthe motor power control device of the present invention.

The control device 15 controls the inverter 17. Thus, the control device15 is able to control the voltage to be supplied to the motor 18independently of controlling the output of the generator 10. Forexample, even while the engine 14 and the generator 10 are operating,the control device 15 is able to bring the motor 18 into a stopped stateby stopping the supply of the voltage to the motor 18. This provides anincreased degree of freedom in terms of controlling the output of thetransmission T.

The adjustment made by the inverter 17 is different from controlling thecurrent by changing the inductance of the generator 10. The adjustmentmade by the inverter 17 is implemented so as to limit the voltagesupplied from the generator 10. The following description will be givenunder the assumption that the limiting of the current made by theinverter 17 is kept minimum.

The inverter 17 may be included in the motor 18. In a case where a DCmotor is adopted as the motor 18, the inverter 17 is not provided.

The control device 15 controls a torque to be outputted from thetransmission T, in accordance with a torque request requesting a torqueto be outputted to the drive wheels Wc, Wd. In this embodiment, both thecontrol device 15 and the engine control device EC (see FIG. 1) receivethe torque request. The control device 15 cooperates with the enginecontrol device EC. More specifically, both the control device 15 and theengine control device EC receive a signal representing the torquerequest from the request indication device A. The control device 15 andthe engine control device EC communicate with each other.

The control device 15 controls the torque to be outputted from the motor18. In more detail, the control device 15 controls the current to besupplied from the generator 10 to the motor 18. Upon a requirement forincreasing the torque, the control device 15 performs a control so as toincrease the current to be supplied to the motor 18.

The control device 15 is connected to the supply current adjustmentdevice 131 of the generator 10. The control device 15 controls thesupply current adjustment device 131 in accordance with the torquerequest outputted from the request indication device A.

The control device 15 also controls the converter 16 and the inverter17.

The control device 15 includes a torque request receiving device 151 andan adjustment control device 152.

The control device 15 is constituted of a microcontroller. The controldevice 15 includes a central processing unit (not shown) and a storagedevice (not shown). The central processing unit performs computationalprocessing based on a control program. The storage device stores dataconcerning programs and computation. The torque request receiving device151 and the adjustment control device 152 are implemented by the centralprocessing unit executing programs.

The torque request receiving device 151 receives a torque request. Thetorque request receiving device 151 receives the torque request from therequest indication device A.

The adjustment control device 152 controls the supply current adjustmentdevice 131. Thus, the supply current adjustment device 131 controls thecurrent to be supplied to the motor 18.

If the torque request received by the torque request receiving device151 is a request for increasing the torque to be outputted from thetransmission T to the drive wheels Wc, Wd, the adjustment control device152 performs the control so as to increase the current to be supplied tothe motor 18. That is, to increase the output power of the motor 18, theadjustment control device 152 performs the control so as to increase thecurrent to be supplied to the motor 18.

[Supply Current Adjustment Device]

FIG. 3A and FIG. 3B are schematic diagrams for explanation of adjustmentmade by the supply current adjustment device 131 provided in thegenerator 10 shown in FIG. 2. FIG. 3A shows a state in which theinductance of the winding 121 is set to the highest settable value. FIG.3B shows a state in which the inductance of the winding 121 is set to avalue lower than that of FIG. 3A.

FIG. 3A illustrates a part of the rotor 11 and a part of the stator 12provided in the generator 10. The generator 10 of this embodimentincludes an SPM (Surface Permanent Magnet) generator. The rotor 11 andthe stator 12 are opposite to each other. More specifically, themagnetic pole parts 111 of the rotor 11 and the teeth 122 b of thestator core 122 of the stator 12 are opposite to each other with the airgap therebetween. The magnetic pole parts 111 are exposed to the stator12.

The supply current adjustment device 131 changes the magnetic resistanceof a magnetic circuit F2 for the winding 121, which passes through thestator core 122. In this manner, the supply current adjustment device131 changes the inductance of the winding 121, to adjust the current tobe supplied to the motor 18. In more detail, the supply currentadjustment device 131 moves the position of the stator core 122 relativeto the winding 121. This is how the supply current adjustment device 131changes the magnetic resistance of the magnetic circuit for the winding121, which passes through the stator core 122.

The windings 121 are secured to a casing (not shown) of the generator10. The stator core 122 is supported on the casing such that the statorcore 122 is freely movable in the axial direction X relative to thewindings 121. The windings 121 are not secured to the teeth 122 b. A gapis ensured between each winding 121 having a cylindrical shape and eachtooth 122 b. The gap is to such an extent that the tooth 122 b is freelymovable relative to the winding 121.

The supply current adjustment device 131 moves the stator core 122 so asto move the teeth 122 b in a direction into and out of the cylindricallywound windings 121. In this embodiment, the supply current adjustmentdevice 131 moves the stator core 122 in the axial direction X. Thecontrol device 15 operates the supply current adjustment device 131 inaccordance with the torque request.

In FIGS. 3A and 3B, for the purpose of describing the movement of thestator core 122 in an easy-to-understand manner, the supply currentadjustment device 131 is schematically illustrated in the form of arack-and-pinion mechanism and a motor. Here, mechanisms other than theillustrated one are adoptable as the supply current adjustment device131 that moves the stator core 122. For example, a mechanism including acylindrical member that is arranged concentric with a stator core inthreaded engagement with the stator core is adoptable. Such a mechanismis able to move the stator core in the axial direction X by, forexample, rotating the cylindrical member relative to the stator core.

The supply current adjustment device 131 moves the position of thestator core 122 relative to the winding 121 while maintaining theposition of the stator core 122 relative to the rotor 11. In FIGS. 3Aand 3B, the broken lines Q express that the rotor 11 moves inconjunction with the stator core 122 in the axial direction X. Astructure for maintaining the relative position between the rotor 11 andthe stator core 122 is implemented by, for example, a bearing part 113rotatably supporting the rotor 11. The position of the bearing part 113is fixed relative to the stator core 122.

FIG. 3A and FIG. 3B illustrate primary magnetic fluxes F1 generated bythe magnetic pole parts 111. The line of each magnetic flux F1represents a primary magnetic circuit through which the magnetic flux F1generated by the magnetic pole part 111 flows. The magnetic circuitthrough which the magnetic flux F1 flows will be referred to as amagnetic circuit F1

The primary magnetic flux F1 generated by the magnetic pole part 111flows through the magnetic pole part 111, the air gap between themagnetic pole part 111 and the tooth 122 b, the tooth 122 b, the coremain body 122 a, and the back yoke part 112. In other words, themagnetic circuit F1 is made up of the magnetic pole part 111, the airgap between the magnetic pole part 111 and the tooth 122 b, the tooth122 b, the core main body 122 a, and the back yoke part 112.

Here, FIG. 3A and FIG. 3B show three teeth 122 b among the plurality ofteeth 122 b arranged in the circumferential direction. For providingplain illustration of the magnetic circuits F1, FIG. 3A and FIG. 3B showa state in which the magnetic pole part 111 is opposite to the middletooth 122 b among the three teeth 122 b.

As the rotor 11 rotates, the amount of magnetic flux generated by themagnetic pole part 111 and linked with the winding 121 changes. Thechange of the amount of magnetic flux linked with the winding 121 causesan induced voltage to occur in the winding 121. That is, power isgenerated.

The induced voltage caused in the winding 121 depends on the amount ofmagnetic flux linked with the winding 121. The higher the magneticresistance of the magnetic circuit F1 is, the smaller the amount ofmagnetic flux linked with the winding 121 is. The magnetic resistance ofthe magnetic circuit F1 depends mainly on the magnetic resistance of theair gap between the tooth 122 b and the magnetic pole part 111. Themagnetic resistance of the air gap between the tooth 122 b and themagnetic pole part 111 depends on an air gap length L1 of the air gapbetween the tooth 122 b and the magnetic pole part 111.

Accordingly, the induced voltage caused in the winding 121 depends onthe air gap length L1 of the air gap between the tooth 122 b and themagnetic pole part 111.

FIG. 3A and FIG. 3B illustrate a primary magnetic flux F2 generated by acurrent flowing in the winding 121. At a time of power generation, acurrent caused by the induced voltage flows in the winding 121. Themagnetic flux F2 is generated by the current flowing in the winding 121at the time of power generation. The line of each magnetic flux F2represents a primary magnetic circuit through which the magnetic flux F2generated by the current in the winding 121 flows. The magnetic circuitthrough which the magnetic flux F2 flows will be referred to as amagnetic circuit F2. The magnetic circuit F2 is the magnetic circuit forthe winding 121. The magnetic circuit F2 for the winding 121 is made upof a path passing through the inside of the winding 121 and providingthe minimum magnetic resistance of the entire magnetic circuit F2.

The magnetic circuit F2 passes through the stator core 122. The magneticcircuit F2 passes through adjacent teeth 122 b. In the drawing, threeteeth 122 b among the plurality of teeth 122 b arranged in thecircumferential direction are shown. The magnetic circuit F2 for thewinding 121 wound on the middle tooth 122 b among the three teeth 122 bis illustrated as a typical example. A magnetic circuit F2 for a certainwinding 121 passes through a tooth 122 b having the certain winding 121wound thereon and two teeth 122 b adjacent to the certain tooth 122 b.

The primary magnetic flux F2 generated by the current in the winding 121flows through the teeth 122 b, the core main body 122 a, and the air gapbetween the two adjacent teeth 122 b. In other words, the magneticcircuit F2 is made up of the teeth 122 b, the core main body 122 a, andthe air gap between the two adjacent teeth 122 b. The magnetic circuitF2 passing through the stator core 122 includes one air gap. A portionof the magnetic circuit F2 including the air gap is indicated by thebold line. The bold-line portion of the magnetic circuit F2 includingthe air gap will be simply referred to as an air gap F2 a. The air gapF2 a exists between the winding 121 and the rotor 11. The air gap F2 aincluded in the magnetic circuit F2 exists between the winding 121 andthe rotor 11 and between the adjacent teeth 122 b. The air gap F2 a is anon-magnetic gap. A portion of the magnetic circuit F2 corresponding tothe air gap F2 a is provided so as to connect respective portions of thetwo adjacent teeth 122 b opposite to the rotor 11.

The magnetic circuit F2 for the winding 121 includes the air gap F2 abetween the two adjacent teeth 122 b. The magnetic circuit F2 doessubstantially not include the back yoke part 112 of the rotor 11. Mostof the magnetic flux F2 generated by the current in the winding 121flows through the air gap between the two adjacent teeth 122 b withoutgoing to the back yoke part 112 of the rotor 11, for the followingreasons.

For the magnetic flux F2 generated by the current in the winding 121,the magnetic pole part 111 is considered simply as a magnetic flux path.In this embodiment, the magnetic pole part 111 is made of a permanentmagnet whose magnetic permeability is as low as air. The magnetic polepart 111 can therefore be considered as equivalent to air for themagnetic circuit F2. Since the magnetic pole part 111 is equivalent toair, the substantial air gap length of the air gap between the stator 12and the rotor 11 is equal to a distance L11 from the tooth 122 b to theback yoke part 112. The distance L11 from the tooth 122 b to the backyoke part 112 includes the thickness of the magnetic pole part 111 withrespect to the axial direction X. Thus, the distance L11 is longer thana distance L1 from the tooth 122 b to the magnetic pole part 111.

In this embodiment, moreover, the amount of the magnetic flux F2generated by the current in the winding 121 is smaller than the amountof magnetic flux generated by the permanent magnet of the magnetic polepart 111. Most of the magnetic flux F2 generated by the current in thewinding 121 is less likely to reach the back yoke part 112 across theair gap length L11. Little of the magnetic flux F2 generated by thecurrent in the winding 121 flows through the back yoke part 112. Alength of a gap hereinafter refers to a width of the gap.

Thus, Most of the magnetic flux F2 generated by the current in thewinding 121 flows through the air gap F2 a between the teeth 122 brather than through the back yoke part 112 of the rotor 11. In the stateshown in FIG. 3A, the inductance of the winding 121 is set to thehighest settable value. In the state shown in FIG. 3A, the air gap F2 aincluded in the magnetic circuit F2 has the highest magnetic resistanceamong portions of the magnetic circuit F2. The air gap F2 a has a highermagnetic resistance than that of a remaining portion F2 b of themagnetic circuit F2 other than the air gap F2 a.

Accordingly, the ratio of a flux component flowing through the air gapbetween the teeth 122 b to a flux component flowing through the backyoke part 112 of the rotor 11 is higher in the magnetic flux F2 than inthe magnetic flux F1 which is generated by the magnetic pole part 111.

The inductance of the winding 121 depends on the magnetic resistance forthe winding 121. The inductance of the winding 121 is in reverseproportion to the magnetic resistance for the winding 121.

Here, the magnetic resistance for the winding 121 is the magneticresistance of the magnetic circuit F2 through which the magnetic flux F2generated by the current in the winding 121 flows. The magneticresistance of the stator core 122, which is the magnetic resistance forthe winding 121, includes the magnetic resistance of the air gap F2 abetween the two adjacent teeth 122 b. In a strict sense, the magneticflux F2 generated by the current in the winding 121 flows through boththe stator 12 and the rotor 11. As described above, however, most of themagnetic flux generated by the current in the winding 121 flows throughthe air gap between the two adjacent teeth 122 b without going to theback yoke part 112 of the rotor 11. Therefore, the magnetic resistanceto the winding 121 depends more strongly on the magnetic resistance ofthe magnetic circuit F2 passing through the stator 12 than on themagnetic resistance of the magnetic circuit F1 passing through the rotor11. That is, the inductance of the winding 121 depends more strongly onthe magnetic resistance of the magnetic circuit F2, which passes throughthe stator core 122 when viewed from the winding 121 side, than on themagnetic resistance of the magnetic circuit F1, which passes through therotor 11 when viewed from the winding 121 side. Accordingly, theinductance of the winding 121 substantially depends on the magneticresistance of the magnetic circuit F2, which passes through the statorcore 122 when viewed from the winding 121 side.

The supply current adjustment device 131 moves the position of thestator core 122 relative to the windings 121. In this manner, the supplycurrent adjustment device 131 changes the magnetic resistance of themagnetic circuit F2 for the winding 121, which passes through the statorcore 122. This is how the supply current adjustment device 131 changesthe inductance of the winding 121. For example, in case of the supplycurrent adjustment device 131 moving the stator core 122 in a directionindicated by the arrow X1, the teeth 122 b of the stator core 122 aremoved in the direction out of the cylindrically wound windings 121.

FIG. 3B shows a state having a lower inductance than that of the stateshown in FIG. 3A.

Since the teeth 122 b of the stator core 122 are moved out of thewindings 121, the volume of the stator core 122 existing within thewindings 121 is reduced. As a result, the magnetic flux within thewinding 121 spreads. From the viewpoint of the magnetic circuit F2 forthe winding 121, the length of the air gap F2 a constituting themagnetic circuit F2 increases. This increases the magnetic resistance ofthe air gap F2 a between the winding 121 and the rotor 11. That is, themagnetic resistance of the air gap F2 a, whose magnetic resistance ishighest, increases. As a result, the magnetic resistance of the magneticcircuit F2 for the winding 121, which passes through the stator core122, increases. Consequently, the inductance of the winding 121decreases.

The supply current adjustment device 131 changes the magnetic resistanceof the air gap F2 a whose magnetic resistance is highest. In thismanner, the supply current adjustment device 131 changes the magneticresistance of the magnetic circuit F2 passing through the adjacent teeth122 b. This can cause a larger change of the inductance of the winding121 as compared with, for example, changing the magnetic resistance of aportion other than the air gap F2 a.

Furthermore, the supply current adjustment device 131 changes theinductance of the winding 121 such that the change rate of theinductance of the winding 121 is higher than the change rate of themagnetic flux linked with the winding 121. This is how the supplycurrent adjustment device 131 adjusts the current. The supply currentadjustment device 131 of the generator 10 according to this embodimentmoves the position of the stator core 122 relative to the windings 121while maintaining the position of the stator core 122 relative to therotor 11.

As the supply current adjustment device 131 moves the stator core 122 inthe direction of the arrow X1, the rotor 11 is accordingly moved in thedirection of the arrow X1. Therefore, the position of the stator core122 relative to the rotor 11 is maintained. This can suppress a changeof the air gap length L1 between the teeth 122 b and the magnetic poleparts 111, which otherwise might be caused by movement of the statorcore 122. Accordingly, a change of the magnetic flux F1 flowing from themagnetic pole part 111 to the stator core 122 is suppressed. That is, achange of the magnetic flux F1 linked with the winding 121 issuppressed.

FIG. 4 is a circuit diagram schematically showing an equivalent circuitof the winding 121 of the generator 10 shown in FIG. 3A.

The circuit depicted in FIG. 4 is simplified for the purpose ofoutlining a change of the voltage and current generated by the generator10. In addition, illustration of the converter 16 and the inverter 17 isomitted on the assumption that their states are fixed.

As shown in FIG. 4, the winding 121 in an electrical sense includes anAC voltage source 121A, an inductor 121B, and a resistance 121C.

The AC voltage source 121A outputs an induced voltage E which dependsmainly on a magnetic flux Φ linked with the winding 121. Morespecifically, the induced voltage E depends on the product of themagnetic flux F1 and the rotation speed ω of the rotor 11. An inductanceL of the inductor 121B depends mainly on the magnetic resistance of thestator core 122 for the winding 121. A resistance value R of theresistance 121C is a winding resistance. Impedance Zg of the winding 121is schematically expressed as ((ωL)²+R²)^(1/2).

The supply current adjustment device 131 moves the position of thestator core 122 relative to the winding 121 in accordance with thecurrent request. Thus, the supply current adjustment device 131 changesthe magnetic resistance of the magnetic circuit F2 for the winding 121,which passes through the stator core 122. Thus, the supply currentadjustment device 131 changes the inductance L of the winding 121. Thechange of the inductance L leads to a change of the impedance Zg. As aresult, a current I to be supplied from the generator 10 is adjusted.

The supply current adjustment device 131 changes the inductance of thewinding 121 such that the change rate of the magnetic flux Φ linked withthe winding 121 is lower than the change rate of the inductance L of thewinding 121. This is how the supply current adjustment device 131adjusts the current I. Accordingly, the current is adjusted with lesschange of the induced voltage E.

Instead of making adjustment by the supply current adjustment device131, changing the output (rotational power) of the engine 14 is alsoconceivable as a method for adjusting the current outputted from thegenerator 10. The engine output adjustment device 141 changes therotation speed of the engine 14, to change the rotation speed ω of therotor 11, so that the voltage to be supplied to the motor 18 isadjusted.

The output (rotational power) of the engine 14 mainly changes therotation speed of the output shaft C, that is, the rotation speed ω ofthe rotor 11. The rotation speed ω of the rotor 11 influences both theinduced voltage E of the winding 121 and the impedance ((ωL)²+R²)^(1/2).Therefore, adoption of only the method of changing the rotation speed ofthe output shaft C of the engine 14 cannot avoid high interactionbetween the supply voltage and the supply current.

In this respect, the generator 10 moves the position of the stator core122 relative to the winding 121 in accordance with the torque requestwhich corresponds to the current request, to change the magneticresistance of the magnetic circuit F2 for the winding 121, which passesthrough the stator core 122. As a result, the inductance of the winding121 is changed. Therefore, the ratio of a current change to a voltagechange obtained when changing the magnetic resistance of the magneticcircuit F2 for the winding 121 is different from that obtained whenchanging the rotation speed ω of the rotor 11. Accordingly, thegenerator 10 of this embodiment is able to adjust the current to besupplied to the motor 18 with less interaction between the voltagechange and the current change as compared with when, for example, onlythe rotation speed of the output shaft C of the engine 14 is changed bythe engine output adjustment device 141.

In this embodiment, a movement of the position of the stator core 122relative to the winding 121 causes a change of the magnetic resistanceof the magnetic circuit F2 for the winding 121, which passes through thestator core 122. As a result, the inductance L of the winding 121 ischanged, so that the current is adjusted. This embodiment can graduallychange the inductance L because the change of the inductance L isimplemented by a change of the magnetic resistance of the stator core122 for the winding 121.

Instead of changing the magnetic resistance of the magnetic circuit forthe winding which passes through the stator core, changing thesubstantial number of turns of the winding is also conceivable as amethod for changing the inductance. For example, it is conceivable thata terminal provided at an end of the winding and a terminal provided inthe middle of the winding are selectively switched for use as a currentoutput terminal. It is also conceivable that a terminal provided in themiddle of the winding is short-circuited to another terminal. Thischanges the substantial number of turns which affect the current. As aresult, the inductance is changed.

Here, in a case of changing the substantial number of turns of thewinding, such a change of the substantial number of turns is causedsignificantly and instantaneously. Therefore, an excessive voltageoccurs in the winding. In addition, an excessive current is likely toflow in a short time. In a case of changing the substantial number ofturns, it is required that a switching element for switching the currentis provided. Furthermore, the switching element needs to have a highbreakdown voltage in order to withstand the excessive voltage. Thewinding needs to be made of a thick wire in order to deal with a changeof the excessive current. For these reasons, changing the substantialnumber of turns of the winding is less efficient. In addition, itinvolves a size increase of the generator.

In this embodiment, the magnetic resistance of the stator core 122 ischanged, so that the inductance L of the winding 121 is changed. Thus,the inductance L of the winding 121 can be changed gradually. This cansuppress a rapid increase of the voltage occurring in the winding 121.It is therefore possible that a component having a low breakdown voltageis connected to the generator 10. This provides a high efficiency. Thisalso eliminates the need to provide the switching element for switchingthe current. This also allows use of a relatively thin wire for thewinding. A size increase of the generator 10 is suppressed.

[Control of Torque and Speed]

FIG. 5 is a flowchart of the operation of the transmission T.

Rotational power outputted from the transmission T to the drive wheelsWc, Wd is controlled in both the engine 14 and the transmission T. Therotational power is controlled by the control device 15 and the enginecontrol device EC. In this embodiment, the control device 15 and theengine control device EC cooperate with each other. In the following,therefore, the operation of the engine 14 as well as the operation ofthe transmission T will be described.

The control device 15 of the transmission T controls the current andvoltage to be supplied to the motor 18. The control device 15 repeats acontrol process shown in FIG. 5.

The torque request receiving device 151 of the control device 15 and theengine control device EC receive a request for rotational power (S11).The torque request receiving device 151 receives a torque request. Thetorque request represents a request for a torque to be outputted fromthe transmission T. The torque request receiving device 151 receives theamount of operation of the request indication device A. The torquerequest receiving device 151 obtains the torque request based on theamount of operation of the request indication device A. Morespecifically, the torque request receiving device 151 obtains the torquerequest based on the amount of operation of the request indicationdevice A, the state of traveling of the vehicle V setting of the targetfuel efficiency, and setting of the followability to the operation. Thetorque request receiving device 151 obtains both a request for thetorque and a request for the rotation speed.

Then, the adjustment control device 152 of the control device 15 and theengine control device EC control the rotational power based on therequest received (S12). The adjustment control device 152 and the enginecontrol device EC control the supply current adjustment device 131 andthe engine output adjustment device 141, respectively, in accordancewith the request received (S12). The adjustment control device 152controls the torque to be outputted from the transmission T based on therequest received by the torque request receiving device 151. Upon arequest for increasing the torque, the adjustment control device 152controls the torque to be outputted from the transmission T. In moredetail, upon a request for increasing the torque, the adjustment controldevice 152 performs the control so as to increase the torque to beoutputted from the transmission T. The adjustment control device 152controls the torque and the rotation speed to be outputted from thetransmission T.

The adjustment control device 152 cooperates with the engine controldevice EC to control the torque and the rotation speed to be outputtedfrom the transmission T. The adjustment control device 152 and theengine control device EC control the amount of adjustment made by thesupply current adjustment device 131 and the amount of adjustment madeby the engine output adjustment device 141. The adjustment controldevice 152 and the engine control device EC control a distributionbetween the amount of adjustment made by the supply current adjustmentdevice 131 and the amount of adjustment made by the engine outputadjustment device 141.

The adjustment control device 152 controls a distribution between theamount of increase of the torque to be outputted from the transmission Tand the amount of increase of the rotation speed to be outputted fromthe transmission T. As for the control performed by the adjustmentcontrol device 152 and the engine control device EC, a typical exampleof a control with a large amount of increase of the torque and a typicalexample of a control with a large amount of increase of the rotationspeed will be described. The typical example of the control with a largeamount of increase of the torque will be referred to as a torquecontrol. The typical example of the control with a large amount ofincrease of the rotation speed will be referred to as a speed control.The adjustment control device 152 and the engine control device ECperform any of the torque control, the speed control, and a combinationof the torque control and the speed control, in accordance with therequest received.

(Speed Control)

In the speed control, the engine control device EC increases therotational power of the engine 14. To be specific, the engine controldevice EC directs the engine output adjustment device 141 to increasethe amount of air taken in and the amount of fuel injected by the engine14. The increase of the power of the engine 14 leads to an increase ofthe rotation speed of the engine 14 which means the rotation speed ω ofthe rotor 11 of the generator 10.

In the speed control, the control device 15 does not direct the supplycurrent adjustment device 131 to perform the adjustment for reducing theinductance L of the winding 121. The supply current adjustment device131 maintains the state in which the teeth 122 b of the stator core 122are completely received in the cylindrical shapes of the windings 121,as shown in FIGS. 3A and 3B.

As the rotation speed ω increases, the induced voltage E of the ACvoltage source 121A shown in FIG. 4 increases. The induced voltage E issubstantially in proportion to the rotation speed ω. This results in anincrease of the voltage outputted from the transmission T. That is, thevoltage supplied to the motor 18 increases. As a result, the rotationspeed of the motor 18 increases.

(Torque Control)

In the torque control, the control device 15 directs the supply currentadjustment device 131 to adjust the position of the stator core 122 soas to reduce the inductance L of the winding 121. The supply currentadjustment device 131 adjusts the position of the stator core 122 so asto increase the magnetic resistance of the stator core 122 for thewinding 121. In this embodiment, the supply current adjustment device131 moves the stator core 122 in such a direction that the teeth 122 bof the stator core 122 are moved out of the cylindrical shapes of thewindings 121 shown in FIGS. 3A and 3B. As a result, the inductance L ofthe winding 121 is reduced.

In the transmission T, the control device 15 directs the supply currentadjustment device 131 to adjust the magnetic resistance of the magneticcircuit F2 for the winding 121 in accordance with the torque request.The control device 15 directs the supply current adjustment device 131to adjust the magnetic resistance of the magnetic circuit F2 for thewinding 121 in accordance with the current request corresponding to thetorque request. In this manner, the supply current adjustment device 131changes the inductance of the winding 121. This is how to control thecurrent to be supplied to the motor 18 serving as the electrical loaddevice.

In the transmission T, for example, the control device 15 directs thesupply current adjustment device 131 to increase the magnetic resistanceof the magnetic circuit F2 for the winding 121, in accordance with arequest for increasing the torque. In the transmission T, the controldevice 15 directs the supply current adjustment device 131 to increasethe magnetic resistance of the magnetic circuit F2 for the winding 121,in accordance with a request for increasing the current, whichcorresponds to a request for increasing the torque. Thus, the supplycurrent adjustment device 131 reduces the inductance of the winding 121.This can increase the current to be supplied to the motor 18 serving asthe electrical load device.

The supply current adjustment device 131 changes the inductance of thewinding 121 by changing the magnetic resistance of the air gap F2 aexisting between the winding 121 and the rotor 11. The magnetic poleparts 111 moving along with rotation of the rotor 11 cause analternating magnetic field to occur between the windings 121 and therotor 11. For example, reducing the magnetic resistance of the air gapF2 a existing between the winding 121 and the rotor 11 leads to areduction of an alternating magnetic field loss. To be exact, a coreloss in the magnetic circuit F2 passing through the air gap F2 a isreduced. The reduction of the loss enables a large current to beoutputted. Accordingly, the current to be supplied to the motor 18serving as the electrical load device can be adjusted to an increaseddegree.

In the torque control, moreover, the engine control device EC directsthe engine output adjustment device 141 (FIG. 2) to increase therotational power of the engine 14. To be specific, the engine controldevice EC directs the engine output adjustment device 141 to increasethe amount of air taken in and the amount of fuel injected by the engine14. The increase of the rotational power of the engine 14 leads to anincrease of the rotation speed of the engine 14 which means the rotationspeed ω of the rotor 11 of the generator 10.

As the rotation speed ω increases, the induced voltage E of the ACvoltage source 121A increases. The induced voltage E is substantially inproportion to the rotation speed ω. The increase of the induced voltageE results in an increase of the current outputted from the generator 10.That is, the current supplied to the motor 18 increases. As a result,the torque of the motor 18 increases.

The control device 15 and the engine control device EC perform thecontrol by using, for example, a map in which the inductance, therotation speed of the rotor 11, and the output current are stored inassociation with one another. The map is obtained based on the followingrelationships (i) and (ii), for example. The relationship (i) is therelationship between the rotation speed of the engine 14 and the inputcurrent of the motor 18. The relationship (ii) is the relationshipbetween the torque and the rotation speed of the motor 18. Therelationship (i) is specified or set based on, for example, measurementor simulation of the generator which have been preliminarily conductedfor a plurality of conditions of the inductance L. The relationship (i)includes the relationship between the rotation speed and the outputcurrent of the generator 10 as shown in FIG. 9, for example. Therelationship (i) also includes an influence of the operations of theconverter 16 and the inverter 17. The relationship (ii) is specified orset based on, for example, a result of measurement or simulation of themotor which have been preliminarily conducted.

For example, the control device 15 determines, as a target, the inputcurrent of the motor 18 corresponding to the requested torque of thetransmission T. For example, the control device 15 controls the supplycurrent adjustment device 131 so as to obtain the inductance L thatallows the target current to be supplied at the minimum rotation speedof the generator 10.

The engine control device EC operates the engine 14 at such a rotationspeed that allows the target current to be supplied under the conditionof the inductance L obtained by the control device 15. In a case wherethe current and the voltage are limited by the converter 16 and theinverter 17, the rotation speed is adjusted based on an influence of thelimiting.

Here, it may be acceptable that the control device 15 and the enginecontrol device EC control the supply current adjustment device 131without using the map. For example, the control performed by the controldevice 15 and the engine control device EC may be based on a result ofcomputation of expressions.

The control device 15 and the engine control device EC are configured tocooperate with each other to control the supply current adjustmentdevice 131 and the engine output adjustment device 141, respectively.For example, the control device 15 transmits information of the requiredrotation speed to the engine control device EC.

Preferably, an entire period in which the supply current adjustmentdevice 131 reduces the inductance of the winding 121 has an overlap withan entire period in which the engine output adjustment device 141increases the rotational power of the engine 14. Preferably, a period inwhich the supply current adjustment device 131 is reducing theinductance of the winding 121 has an overlap with a period in which theengine output adjustment device 141 is increasing the rotational powerof the engine 14.

In this embodiment, upon a requirement for increasing the torque, theengine 14 increases the rotational power of its output shaft C by meansof the adjustment made by the engine output adjustment device 141. As aresult, the rotation speed ω of the rotor 11 of the generator 10increases. On the other hand, the transmission T reduces the inductanceL of the winding 121 by means of the adjustment made by the supplycurrent adjustment device 131. As a result, an increase of the impedanceZg of the winding 121, which depends on the product of the rotationspeed ω and the inductance L, is suppressed. This provides a greaterincrease of the current outputted from the generator 10 as compared withwhen, for example, the inductance L of the winding 121 is not reduced.Accordingly, a greater increase of the torque outputted from thetransmission T is obtained as compared with when, for example, theinductance L of the winding 121 is not reduced.

Thus, even though the condition about the rotational power of the engine14 is constant, the torque outputted from the transmission T changes inaccordance with the adjustment performed in the transmission T. In thetransmission T, moreover, the torque adjustment range of the torqueoutputted from the transmission T is enlarged by performing the torquecontrol.

To respond to a request for an increase of the torque, for example, itis conceivable to increase the rotational power of the engine 14 withoutreducing the inductance L of the winding 121.

In such a case, as the rotational power increases, the rotation speed ωof the rotor increases. The induced voltage increases accordingly. Theincrease of the rotation speed ω also increases the impedance Zg of thewinding. Therefore, the increase of the current supplied to the motor issmaller than the increase of the rotational power. As a result, theamount of increase of the torque is small.

Increasing the rotational power of the engine 14 without reducing theinductance L of the winding 121 for the purpose of increasing thecurrent results in an excessive increase of the rotational power of theengine 14 relative to an increase of the power generation current. Theexcessive increase of the rotational power decreases the fuel efficiencyof the engine 14.

In addition, the excessive increase of the rotational power causes anexcessive increase of the induced voltage E. For example, in a situationwhere the rotation speed of the motor 18 becomes substantially constantafter increasing, the current supplied to the motor 18 decreases. Thismakes the impedance Zg of the winding 121 less influential. Accordingly,a voltage corresponding to the induced voltage E, which has excessivelyincreased, is outputted from the generator 10. Moreover, the converter16 is arranged between the generator 10 and the motor 18. A high voltagecorresponding to the induced voltage E is applied to the switchingelements of the converter 16. In general, a switching element having ahigh breakdown voltage for withstanding a high voltage has a highon-resistance. Thus, a large loss is caused by the switching element.

In this respect, the generator 10 of this embodiment is configured suchthat the supply current adjustment device 131 reduces the inductance Lof the winding 121 in response to a request for an increase of thetorque. As a result, an increase of the impedance Zg of the winding 121is suppressed. This allows a greater increase of the output torque ofthe transmission T to be obtained from the increase of the rotationalpower of the engine 14 as compared with when, for example, theinductance L is not reduced. In this manner, an excessive increase ofthe rotational power of the engine 14 in response to a request forincreasing the torque is suppressed. This improves the fuel efficiencyof the engine. Also, an excessive increase of the output voltage issuppressed. This allows adoption of a switching element with a lowbreakdown voltage, whose on-resistance is low. Accordingly, a highefficiency is obtained.

The transmission T of this embodiment is able to enhance separationbetween the adjustment of the output torque and the adjustment of therotation speed as compared with when, for example, the output of theengine 14 is supplied to the drive wheels Wc, Wd without interpositionof the transmission T. The transmission T is, therefore, able to makeadjustment more responsive to each of the torque requirement and thespeed requirement.

Furthermore, the transmission T of this embodiment controls theconverter 16 and the inverter 17 by means of the control device 15.Thus, the transmission T is able to control the current and voltage tobe supplied to the motor 18 independently of the adjustment made on thegenerator 10. The transmission T is, therefore, able to control thetorque and the rotation speed to be outputted from the motor 18 of thetransmission T independently of the adjustment made on the generator 10.This provides an increased degree of freedom in terms of controlling theoutput of the transmission T.

For example, the transmission T directs the converter 16 and theinverter 17 to stop the supply of electric power to the motor 18. Inthis manner, the transmission T is able to bring the motor 18 into thestopped state even while the engine 14 and the generator 10 areoperating.

Second Embodiment

Next, a second embodiment of the present invention will be described. Inthe description of the second embodiment given below, differences fromthe first embodiment illustrated above will be mainly described.

FIG. 6A and FIG. 6B are schematic diagrams for explanation of adjustmentmade by a supply current adjustment device provided in a generator 20 ofa transmission according to the second embodiment. FIG. 6A shows a statein which the inductance of the winding 221 is set to the highestsettable value. FIG. 6B shows a state in which the inductance of thewinding 221 is set to a value lower than that of FIG. 6A.

The positional relationship among windings 221, a stator core 222, and arotor 21 shown in FIG. 6A is the same as the positional relationshipthereamong in the first embodiment having been described with referenceto FIG. 3A.

A magnetic circuit F21 is a magnetic circuit through which a magneticflux generated by a magnetic pole part 211 flows. A magnetic circuit F22is a magnetic circuit for the winding 221. The magnetic circuit F22 forthe winding 221 is made up of a path passing through the inside of thewinding 221 and providing the minimum magnetic resistance of the entiremagnetic circuit F22. The magnetic circuit F22 passes through the statorcore 222. The magnetic circuit F22 passes through two adjacent teeth 222b.

The magnetic circuit F22 passing through the stator core 222 includes anair gap F22 a. The air gap F22 a exists between the winding 221 and therotor 21. The air gap F22 a included in the magnetic circuit F22 existsbetween the winding 221 and the rotor 21 and between the two adjacentteeth 222 b. The air gap F22 a included in the magnetic circuit F22 isprovided so as to connect respective portions of the two adjacent teeth222 b opposite to the rotor 21.

The magnetic circuit F22 for the winding 221 does not pass through aback yoke part 212 of the rotor 21. The magnetic circuit F22 for thewinding 221 includes the air gap F22 a between the two adjacent teeth122 b.

In the state shown in FIG. 6A, the air gap F22 a included in themagnetic circuit F22 has the highest magnetic resistance among portionsof the magnetic circuit F22. The air gap F22 a has a higher magneticresistance than that of a remaining portion F22 b of the magneticcircuit F22 other than the air gap F22 a.

In the generator 20 shown in FIGS. 6A and 6B, a supply currentadjustment device 231 moves the windings 221. Thus, the supply currentadjustment device 231 changes the magnetic resistance of the magneticcircuit F22 for the winding 221, which passes through the stator core222. Thus, the supply current adjustment device 231 changes theinductance of the winding 221, to adjust the current to be supplied tothe motor 18 (see FIG. 1).

The supply current adjustment device 231 moves the windings 221 withoutmoving the stator core 222 of the stator 22.

More specifically, the stator core 222 is secured to a casing (notshown). The rotor 21 is rotatably supported on the casing. The rotor 21is secured with respect to the axial direction X. The windings 221 aresupported on the casing such that the windings 221 are freely movable inthe axial direction X relative to the casing.

The supply current adjustment device 231 moves the windings 221 in thedirection that causes the teeth 222 b to move into and out of thecylindrical shapes of the windings 221. In this embodiment, the currentadjustment device 231 moves the windings 221 in the axial direction X.The supply current adjustment device 231 moves the windings 221 in adirection indicated by the arrow X2, for example. All the windings 221wound on the teeth 222 b provided in the generator 20 are movedintegrally. The control device 15 operates the supply current adjustmentdevice 231 in accordance with the torque request.

FIG. 6B shows a state having a lower inductance than that of the stateshown in FIG. 6A. The state shown in FIG. 6B is a state after thewindings 221 are moved in the direction of the arrow X2.

In this embodiment, the supply current adjustment device 231 moves thewindings 221 alone, in accordance with the torque request. In thismanner, the supply current adjustment device 231 moves the position ofthe stator core 222 relative to the windings 221. Thus, the supplycurrent adjustment device 231 changes the magnetic resistance of themagnetic circuit F22 for the winding 221, which passes through thestator core 222.

For example, when the windings 221 are moved in the direction of thearrow X2, that is, toward the rotor 21, the teeth 222 b of the statorcore 222 are pulled out of the windings 221. Pulling the teeth 222 b outof the windings 221 reduces the volume of the stator core 222 existingwithin the windings 221. As a result, the length of the air gap F22 aincluded in the magnetic circuit F22 for the winding 221 increases. Thisincreases the magnetic resistance of the air gap F22 a between thewinding 221 and the rotor 21. That is, the magnetic resistance of theair gap F22 a, which has the highest magnetic resistance, is increased.As a result, the magnetic resistance of the magnetic circuit F22 for thewinding 221 increases. Consequently, the inductance of the winding 221decreases.

The supply current adjustment device 231 changes the magnetic resistanceof the air gap F22 a whose magnetic resistance is highest. Thus, thesupply current adjustment device 231 changes the magnetic resistance ofthe magnetic circuit F22 passing through the adjacent teeth 222 b.Accordingly, a larger change of the inductance of the winding 221 islikely to occur as compared with, for example, changing the magneticresistance of the portion F22 b other than the air gap F22 a.

In this manner, the supply current adjustment device 231 changes themagnetic resistance of the magnetic circuit F22 for the winding 221,which passes through the stator core 222. Thus, the supply currentadjustment device 231 changes the inductance of the winding 221.

For example, the supply current adjustment device 231 increases themagnetic resistance of the magnetic circuit F22 for the winding 221 inaccordance with a request for increasing the torque. Thus, the supplycurrent adjustment device 231 increases the magnetic resistance of themagnetic circuit F22 for the winding 221 in accordance with a requestfor increasing the current. Thus, the supply current adjustment device231 reduces the inductance of the winding 221. As a result, the currentto be supplied to the motor 18 (see FIG. 1) can be increased.

The supply current adjustment device 231 changes the inductance of thewinding 221 by changing the magnetic resistance of the air gap F22 aexisting between the winding 221 and the rotor 21. This results in areduction of an alternating magnetic field loss. Accordingly, thecurrent to be supplied to the motor 18 can be adjusted to an increaseddegree.

Third Embodiment

Next, a third embodiment of the present invention will be described. Inthe description of the third embodiment given below, differences fromthe first embodiment illustrated above will be mainly described.

FIG. 7 is a schematic diagram showing a generator 30 of a transmissionaccording to the third embodiment.

A stator core 322 provided in the generator 30 shown in FIG. 7 includesa plurality of first stator core parts 323 and a second stator core part324.

Each of the plurality of first stator core parts 323 is provided with afacing portion 323 a that is opposite to the rotor 31 with an air gaptherebetween. The plurality of first stator core parts 323 are annularlyarranged at intervals. That is, the plurality of first stator core parts323 align in the circumferential direction Z. The plurality of firststator core parts 323 function as primary teeth in the stator 32. In thespecification herein, the first stator core parts 323 may also bereferred to as first teeth 323. The length of the facing portion 323 aof the first stator core part 323 with respect to the circumferentialdirection Z is longer than the length of any portion of the first statorcore part 323 other than the facing portion 323 a with respect to thecircumferential direction Z. A winding 321 is wound on each of the firststator core parts 323.

The second stator core part 324 is arranged at a position opposite tothe rotor 31 across the first stator core parts 323. The second statorcore part 324 is not provided with the facing portion 323 a that facesthe rotor 31. The second stator core part 324 includes a stator yokeportion 324 a having an annular shape and a plurality of second teeth324 b. The second teeth 324 b protrude from the stator yoke portion 324a and toward the first stator core part 323. The number of the secondteeth 324 b is equal to the number of the first stator core parts 323.The stator yoke portion 324 a and the second teeth 324 b may beconfigured such that substantially all of the magnetic fluxes flowingthrough the second teeth 324 b flow through the stator yoke portion 324a. That is, the second teeth 324 b may be formed integral with thestator yoke portion 324 a. Alternatively, the second teeth 324 b may beformed separate from the stator yoke portion 324 a such that they areattachable to the stator yoke portion 324 a. The second teeth 324 b arearranged so as to align in the circumferential direction Z. Theplurality of second teeth 324 b are annularly arranged at intervalsequal to the intervals of the first stator core parts 323.

A supply current adjustment device 331 of the generator 30 of thisembodiment moves the position of a part of the stator core 322 relativeto the winding 321. The supply current adjustment device 331 moves oneof the plurality of first stator core parts 323 and the second statorcore part 324 relative to the other. In this manner, the supply currentadjustment device 331 changes the magnetic resistance of a magneticcircuit F32 for the winding 321. This is how the supply currentadjustment device 331 adjusts the current to be supplied to the motor18.

In more detail, the first stator core parts 323 are secured to a casing(not shown). The second stator core part 324 is supported so as to berotatable in the circumferential direction Z. The supply currentadjustment device 331 rotates the second stator core part 324 in thecircumferential direction Z about the rotation axis of the rotor 31. Inthis manner, the supply current adjustment device 331 moves the secondstator core part 324 from a first state (see FIG. 8A) to a second state(see FIG. 8B).

FIG. 8A is a schematic diagram showing that the stator 32 illustrated inFIG. 7 is in the first state. FIG. 8B is a schematic diagram showingthat the stator 32 illustrated in FIG. 7 is in the second state.

In the state shown in FIG. 8A, the inductance of the winding 321 is setto the highest settable value. In the state shown in FIG. 8B, theinductance of the winding 321 is set to a value lower than that of FIG.8A.

In the first state shown in FIG. 8A, each of the plurality of secondteeth 324 b is positioned with respect to the circumferential directionZ so as to confront each of the plurality of first stator core parts323. In the first state, an air gap length L32 between each of theplurality of first stator core parts 323 and the second stator core part324 is shorter than an air gap length L33 between adjacent ones of theplurality of first stator core parts 323. To be exact, the air gaplength L33 is the length of an air gap formed between respectiveportions of the first stator core parts 323, each of the portionsarranged between the winding 321 and the rotor 31 with respect to adirection in which the rotor 31 and the stator 32 are opposite to eachother.

In the second state shown in FIG. 8B, each of the plurality of secondteeth 324 b is positioned between adjacent ones of the first stator coreparts 323 with respect to the circumferential direction Z. In the secondstate, an air gap length L34 between each of the plurality of firststator core parts 323 and the second stator core part 324 is longer thanthe air gap length L33 between adjacent ones of the plurality of firststator core parts 323.

Adjustment made by the supply current adjustment device 331 of thegenerator 30 according to the third embodiment will be described.

FIG. 8A and FIG. 8B illustrate a magnetic circuit F31 through which amagnetic flux generated by a magnetic pole part 311 flows, and a primarymagnetic flux F32 generated by the current in the winding 321. Themagnetic circuit F32 for the winding 321 is made up of a path passingthrough the inside of the winding 321 and providing the minimum magneticresistance of the entire magnetic circuit F32. The magnetic circuit F32passes through the stator core 322. The magnetic circuit F32 passesthrough adjacent first stator core parts 323 (first teeth 323).

The magnetic circuit F32 includes three air gaps. A portion of themagnetic circuit F32 corresponding to an air gap between the twoadjacent first stator core parts 323 (first teeth 323) will be referredto as an air gap F32 a. Portions of the magnetic circuit F32corresponding to air gaps each between each of the two adjacent firststator core parts 323 (first teeth 323) and the second stator core part324 will be referred to as air gaps F32 c. The air gap F32 a between thetwo adjacent first stator core parts 323 (first teeth 323) existsbetween the winding 321 and the rotor 31. The air gap F32 a included inthe magnetic circuit F32 exists between the winding 321 and the rotor 31and between the two adjacent first stator core parts 323 (first teeth323). The air gap F32 a is provided so as to connect mutually oppositeend surfaces of the respective two adjacent first stator core parts 323(first teeth 323).

In the first state shown in FIG. 8A, the air gap length L32 between eachof the plurality of first stator core parts 323 (first teeth 323) andthe second stator core part 324 is shorter than the air gap length L33between adjacent ones of the plurality of first stator core parts 323(first teeth 323). The air gap length L33 is the largest air gap lengthin the magnetic circuit F32. In the first state, therefore, the air gapF32 a between the adjacent first stator core parts 323 has the highestmagnetic resistance among portions of the magnetic circuit F32 for thewinding 321. The magnetic resistance of the air gap F32 a is higher thanthe magnetic resistance of any of remaining portions F32 b, F32 c, andF32 d of the magnetic circuit F32 other than the air gap F32 a. Themagnetic resistance of the air gap F32 a is higher than the magneticresistance of the air gap F32 c between the first stator core part 323and the second stator core part 324.

The magnetic flux F32 generated by the current in the winding 321 flowsthrough the adjacent first stator core parts 323 and the second statorcore part 324, as shown in FIG. 8A. The magnetic resistance of themagnetic circuit F32 for the winding 321, which passes through thestator core 322, depends on the air gap length L33 between the adjacentfirst stator core parts 323.

The magnetic flux F31 generated by the magnetic pole part 311 flowsthrough the two adjacent first stator core parts 323. The magnetic fluxF31 flows through one magnetic pole part 311, a gap between the magneticpole part 311 and the first stator core part 323, the first stator corepart 323, the second stator core part 324, an adjacent first stator corepart 323, a gap between the first stator core part 323 and the magneticpole part 311, an adjacent magnetic pole part 311, and the back yokepart 312. In the first state shown in FIG. 8A, the magnetic flux F31 ofthe magnetic pole part 311 flows through the two adjacent first statorcore parts 323 and the second stator core part 324.

In the second state shown in FIG. 8B, the air gap length L34 betweeneach of the plurality of first stator core parts 323 and the secondstator core part 324 is longer than the air gap length L33 betweenadjacent ones of the plurality of first stator core parts 323.Therefore, the magnetic resistance of the magnetic circuit F32 for thewinding 321, which passes through the stator core 322, is stronglyinfluenced by the air gap length L34 between the first stator core part323 and the second stator core part 324. As a result, in the secondstate, the magnetic resistance of the magnetic circuit F32 for thewinding 321, which passes through the stator core 322, is higher thanthe magnetic resistance in the first state.

The magnetic flux F31 generated by the magnetic pole part 311 flowsthrough one magnetic pole part 311, the gap between the magnetic polepart 311 and the first stator core part 323, and the first stator corepart 323. The magnetic flux F31 flows from the first stator core part323 directly to the adjacent first stator core part 323. The magneticflux F31 generated by the magnetic pole part 311 flows through a gapbetween the two adjacent first stator core parts 323. In the secondstate, the path of the magnetic flux F31 generated by the magnetic polepart 311 is switched in the above-described manner. In the second state,even if the path of the magnetic flux F31 is not switched, at least aportion of the magnetic flux F31 generated by the magnetic pole part 311is increased, the portion flowing through the gap between the twoadjacent first stator core parts 323. The increase of the portion of themagnetic flux F31 flowing through the gap between the two adjacent firststator core parts 323 leads to a substantial increase of the magneticresistance of the air gap F32 a. This is, in a magnetic sense,equivalent to an increase of the air gap length L33 between the twoadjacent first stator core parts 323. Thus, the magnetic resistance ofthe magnetic circuit F32 including the air gap F32 a is furtherincreased. The change rate of the inductance of the winding 321 ishigher than the change rate of the magnetic flux that is generated bythe magnetic pole part 311 and linked with the winding 321.

As described above, the inductance of the winding 321 is liable to be inreverse proportion to the magnetic resistance for the winding 321.Therefore, the inductance of the winding 321 in the second state islower than the inductance of the winding 321 in the first state.

The supply current adjustment device 331 moves one of the plurality offirst stator core parts 323 and the second stator core part 324 relativeto the other so as to shift from the first state (see FIG. 8A) to thesecond state (see FIG. 8B). In this manner, the supply currentadjustment device 331 changes the magnetic resistance of the magneticcircuit F32 for the winding 321. Thus, the supply current adjustmentdevice 331 changes the inductance of the winding 321. This is how thesupply current adjustment device 331 adjusts the current to be suppliedto the motor 18 (see FIG. 1).

The supply current adjustment device 331 changes the magnetic resistanceof the air gap F32 a. The supply current adjustment device 331 changesthe magnetic resistance of the air gap F32 a without changing the airgap length L33 between the first stator core parts 323 serving as theadjacent teeth. Thus, the supply current adjustment device 331 changesthe magnetic resistance of the magnetic circuit F32 passing through thefirst stator core parts 323 serving as the adjacent teeth. In the firststate, the air gap F32 a has the highest magnetic resistance amongportions of the magnetic circuit F32. Therefore, a change of theinductance of the winding 321 can be greater than that obtained when,for example, changing the magnetic resistance of portions other than theair gap F32 a.

The supply current adjustment device 331 changes the inductance of thewinding 321 by changing the magnetic resistance of the air gap F32 aexisting between the winding 321 and the rotor 31. This results in areduction of an alternating magnetic field loss. Accordingly, thecurrent to be supplied to the motor 18 serving as the electrical loaddevice can be adjusted to an increased degree.

FIG. 9 is a graph showing output current characteristics relative to therotation speed of the rotor 31 of the generator 30 shown in FIG. 7.

In the graph of FIG. 9, the broken line H1 represents the output currentcharacteristics in the first state shown in FIG. 8A. In a case of thegenerator 30 having the output current characteristics represented bythe broken line H1, the generator 30 operates in such a manner that thecombination of the output current and the rotation speed locates in aregion on or below the broken line H1 in the graph of FIG. 9. The solidline H2 represents the output current characteristics in the secondstate shown in FIG. 8B. In a case of the generator 30 having the outputcurrent characteristics represented by the solid line H2, the generator30 operates in such a manner that the combination of the output currentand the rotation speed locates in a region on or below the solid lineH2. Here, the graph of FIG. 9 shows the characteristics obtained when asupply voltage adjustment device 344 (see FIG. 7) is not operated, fordescribing a current control in an easy-to-understand manner.

The adjustment made in the generator 30 will be described with referenceto the graph of FIG. 9.

Focusing on the output current obtained in the first state representedby the broken line H1, the output current increases as the rotationspeed increases. The rotation speed of the rotor 31 is, therefore, alsousable to adjust the output current of the generator 30. The rotationspeed of the rotor 31 corresponds to the rotation speed of the outputshaft C (see FIG. 2) of the engine 14.

In the first state, the increase of the output current in accordancewith the increase of the rotation speed is steep in a region where therotation speed of the rotor 31 is relatively low. In the first state,the increase of the output current in accordance with the increase ofthe rotation speed is gentle in a region where the rotation speed isrelatively high. That is, the change rate of the output current relativeto the change of the rotation speed is low in the region where therotation speed is relatively high.

For example, if the generator 30 is fixed in the first state, asignificant increase of the rotation speed of the rotor 31 is requiredin order to increase the output current in a region where the changerate of the output current relative to the change of the rotation speedis low.

For example, the vehicle V (see FIG. 1) traveling at a high speedrequires a further increase of the output torque of the transmission Twhen the vehicle starts uphill traveling or overtakes another vehicleduring traveling. A request for an increased torque is issued in such asituation.

If the request for an increased torque for achieving furtheracceleration is issued while the state of the supply current adjustmentdevice 331 is fixed, a further increase of the rotation speed of therotor 31, which means the rotation speed of the engine 14, is required.That is, an excessive increase of the rotational power of the engine 14is required in order to increase the output torque.

For example, a situation is assumed in which, when the rotation speed isN1 and the output current is I1, a request for an increased torque isissued so that the current needs to be increased to 12. In thissituation, if the generator 30 is fixed in the first state whichcorresponds to H1 in the graph, an excessive increase of the rotationspeed of the rotor 31 occurs. In other words, an excessive increase ofthe rotation speed of the engine 14 occurs. This decreases the fuelefficiency of the engine 14 itself.

The induced voltage of the winding 321 is substantially in proportion tothe rotation speed of the rotor 31. A significant increase of therotation speed causes a significant increase of the induced voltage. Towithstand the significant increase of the voltage, electrical componentsneed to have a high breakdown voltage. This leads to a decrease inefficiency due to an increased breakdown voltage of the electricalcomponents.

In the torque control, the control device 15 controls the supply currentadjustment device 331 in accordance with the torque request. The torquerequest corresponds to the current request. The control device 15changes the magnetic resistance of the magnetic circuit F32 for thewinding 321, which passes through the stator core 322, in accordancewith the torque request. Thus, the control device 15 changes theinductance of the winding 321. This is how to adjust the current to besupplied to the motor 18. To be more specific, the supply currentadjustment device 331 moves the second stator core part 324 from thefirst state (see FIG. 8A) to the second state (see FIG. 8B). As aresult, the output current characteristics change from the onerepresented by the broken line H1 to the one represented by the solidline H2 in FIG. 9.

For example, the control device 15 directs the supply current adjustmentdevice 331 (see FIG. 7) to move the second stator core part 324 tocreate the second state (see FIG. 8B). Thus, the control device 15reduces the inductance. In addition, the engine control device ECincreases the rotational frequency of the engine 14 to N2. As a result,the output current increases to 12. The torque outputted from thetransmission T increases in accordance with the increase of the outputcurrent.

The control device 15 performs the control in the above-describedmanner. This enlarges the torque adjustment range as compared with when,for example, only the rotational frequency of the engine 14 isincreased.

In the torque control, the engine control device EC and the controldevice 15 cooperate with each other. The control device 15 directs thesupply current adjustment device 331 to adjust the inductance of thewinding while the engine control device EC directs the engine outputadjustment device 141 to adjust the rotational power of the engine. Thecontrol device 15 starts a process of directing the supply currentadjustment device 331 to reduce the inductance of the winding 321 beforea process of increasing the rotational power of the engine 14 isterminated. That is, the control device 15 performs the control suchthat there is an overlap between a period in which the supply currentadjustment device 331 is reducing the inductance of the winding 321 anda period in which the engine output adjustment device 141 is increasingthe rotational power of the engine 14.

This provides a smooth increase of the current supplied from thegenerator to the motor 18. Accordingly, the torque increases smoothly.In addition, occurrence of a situation can be suppressed in which therotational power of the engine excessively increases before the outputcurrent of the generator 30 reaches a current value corresponding to therequested torque in the process of adjusting the rotational power of theengine 14.

Next, a rotation speed control will be described. Upon a request forincreasing the rotation speed, the control device 15 does not reduce theinductance L. The engine control device EC directs the engine outputadjustment device 141 (see FIG. 2) to increase the rotational power ofthe engine 14.

In this embodiment, the control device 15 directs the engine outputadjustment device 141 to increase the rotational power of the engine 14,while maintaining the supply current adjustment device 331 (see FIG. 7)in the first state (see FIG. 8A) which corresponds to the broken line H1in the graph of FIG. 9.

The induced voltage E (see FIG. 4) generated in the generator 30 issubstantially in proportion to the rotation speed ω. In particular, asituation requesting an increase of the voltage generally occurs whenimpedance Zm of the motor 18 itself is high. In such a state, theimpedance Zg of the winding 321 is less influential to the outputvoltage of the generator. Therefore, a voltage according to the inducedvoltage E is outputted from the generator.

The transmission T is able to respond to a request for increasing thespeed, without directing the supply current adjustment device 331 toreduce the inductance L of the winding 321.

In order that, instead of the transmission T of this embodiment, acommonly-used generator that is unable to change the inductance canprovide output current characteristics as represented by the solid lineH2 of FIG. 9, it is necessary to increase the thickness of the windingor the amount of magnets. Increasing the thickness of the winding or theamount of magnets leads to a size increase of the transmission itself.As a result, the mountability to vehicle and the portability of thetransmission T are deteriorated. If a commonly-used generator that isunable to change the inductance is configured so as to provide outputcurrent characteristics as represented by the solid line H2, suchgenerator cannot provide output current characteristics as representedby the broken line H1.

As a method for adjusting the current to be supplied to the motor 18,for example, use of a DC-DC converter is conceivable. A DC-DC converterconfigured to input and output electric power capable of driving thevehicle V however, cannot avoid a size increase of its component such asa built-in transformer in response to an increase of required electricpower.

In the transmission T of this embodiment, the control device 15 controlsthe supply current adjustment device 331 so as to change the magneticresistance of the magnetic circuit F32 for the winding 321, which passesthrough the stator core 322, in accordance with the current request.Thus, the control device 15 changes the inductance of the winding 321.This enables the transmission T to adjust the current in accordance withthe torque request without increasing the thickness of the winding orthe amount of magnets.

Referring to FIG. 7 again, the supply voltage adjustment device 344 ofthe generator 30 will be described.

The generator 30 includes the supply voltage adjustment device 344 inaddition to the supply current adjustment device 331. The supply voltageadjustment device 344 is under control of the control device 15.

The supply voltage adjustment device 344 changes a linkage flux thatflows from the magnetic pole part 311 of the rotor 31 and linked withthe winding 321. In this manner, the supply voltage adjustment device344 changes the induced voltage of the winding 321. This is how thesupply voltage adjustment device 344 adjusts the voltage to be suppliedto the motor 18. To be specific, the supply voltage adjustment device344 moves the rotor 31 in the axial direction X. Thus, the supplyvoltage adjustment device 344 changes an air gap length L31 between therotor 31 and the stator 32. Such a movement of the rotor 31 in the axialdirection X is implemented by, for example, the supply voltageadjustment device 344 configured to move a bearing part 313 in the axialdirection X, the bearing part 313 supporting the rotor 31 in a rotatablemanner. The change of the air gap length L31 between the rotor 31 andthe stator 32 leads to a change of the magnetic resistance between therotor 31 and the stator 32. As a result, the amount of the magnetic fluxgenerated by the magnetic pole part 311 and linked with the winding 321is changed. The voltage generated by the generator 30 is changedaccordingly. Controlling the voltage generated by the generator 30 inthe transmission T provides an increased degree of freedom in terms ofcontrolling the rotational power outputted from the transmission T.

As thus far described, the transmission T of this embodiment is able toadjust the voltage to be supplied to the motor 18 in a way other than bythe engine output adjustment device 141 adjusting the rotational powerof the engine 14. This provides an increased degree of freedom in termsof controlling, with suppression of a decrease in fuel efficiency.

The supply voltage adjustment device 344 is capable of more reduction ofa variation in the linkage flux linked with the winding 321, thevariation caused by the operation of the supply current adjustmentdevice 331, the more reduction achieved in the following manner.

The linkage flux that flows from the magnetic pole part 311 of the rotor31 and linked with the winding 321 flows through the stator core 322.Specifically, the linkage flux that flows from the magnetic pole part311 and linked with the winding 321 flows through the first stator corepart 323 and the second stator core part 324.

In response to the supply current adjustment device 331 moving thesecond stator core part 324 so as to shift from the first state (seeFIG. 8A) to the second state (see FIG. 8B), the air gap length L32, L34between the first stator core part 323 and the second stator core part324 is changed. As a result, the amount of the linkage flux that flowsfrom the magnetic pole part 311 of the rotor 31 and linked with thewinding 321 is changed.

The supply voltage adjustment device 344 changes the air gap length L31between the rotor 31 and the stator 32 so as to compensate for avariation in the linkage flux linked with the winding 321, the variationcaused by the operation of the supply current adjustment device 331.This can reduce the variation in the linkage flux linked with thewinding 321, the variation caused by the operation of the supply currentadjustment device 331.

The supply current adjustment device 331, in combination with thecompensation made by the supply voltage adjustment device 344, is ableto adjust the current while less influenced by voltage constraints.

In the third embodiment described above, the generator 30 includes boththe supply current adjustment device 331 and the supply voltageadjustment device 344. The supply voltage adjustment device, however, isnot indispensable in the transmission of the present invention.

In the third embodiment described above with reference to the currentcharacteristics graph of FIG. 9, the current to be supplied to the motor18 can be adjusted while controlling the inductance. Here, it is to benoted that in the first embodiment and the second embodiment as well,the current to be supplied to the motor 18 can be adjusted whilecontrolling the inductance.

The first stator core part 323, which is illustrated as an example ofthe first stator core part in the third embodiment above, has, in itsend portion opposite to the rotor, protruding portions protruding in thecircumferential direction Z which means the direction in which the firststator core parts are arranged side by side. It is however not alwaysnecessary that the first stator core part of the present inventionincludes the protruding portions.

In the embodiments described above, the rotor and the stator having anaxial gap structure are illustrated as an example. The transmission ofthe present invention is also applicable to a radial gap structure inwhich a rotor and a stator are opposite to each other with an air gaptherebetween with respect to a radial direction. The axial direction X(FIGS. 3A and 3B) defined in the axial gap structure of theseembodiments is one example of the direction in which the rotor and thestator of the present invention are opposite to each other. In theradial gap structure, the rotor and the stator are opposite to eachother with respect to the radial direction.

In the embodiments described above, the generator including an SPMgenerator is illustrated as an example. Alternatively, the generator ofthe present invention may be an IPM (Interior Permanent Magnet)generator.

The air gap illustrated in the embodiments described above is oneexample of the non-magnetic gap. The non-magnetic gap is a gap made of asingle type of a non-magnetic material or a plurality of types ofnon-magnetic materials. No particular limitation is put on thenon-magnetic material. Examples of the non-magnetic material includeair, aluminum, and resins. The non-magnetic gap includes at least an airgap.

In the embodiments described above, the configuration in which the rotor11 is connected directly to the output shaft C of the engine 14 isillustrated as a specific example of the configuration in which therotor 11 is connected to the engine 14. Here, the output shaft C of theengine 14 and the rotor 11 of the generator 10 may be connected withinterposition of a transmission mechanism as typified by a belt, a gear,or a drive shaft.

In the embodiments described above, the control device 15 and the enginecontrol device EC configured to receive the torque request and the speedrequest from the request indication device A are illustrated as anexample of the control device. This, however, is not limiting thepresent invention. In a possible example, the control device may beconfigured to receive a torque request from a device that outputs thetorque request and a speed request from another device that outputs thespeed request.

The control device of the present invention does not always have tocommunicate with the engine control device. In a possible example, thecontrol device and the engine control device may share a common controlmap, and receive the same torque request from a request indicationdevice that is provided in common to them. Since they perform controlsbased on the same torque request, the control device performs thecontrol in cooperation with the engine control device.

Moreover, the control device may be integrated with the engine controldevice. For example, the control device may be built on a substrate orelectronic device that is shared with the engine control device.

In the description, the control device 15 and the engine control deviceEC configured to perform the torque control, the speed control, or thecombination of the torque control and the speed control are illustrated.The control device and the engine control device, however, may performthe speed control and the torque control alone. Alternatively, thecontrol device may perform the torque control alone.

In the embodiments described above, the accelerator operator isillustrated as an example of the request indication device A. Here, thetorque request issued to the transmission of the present invention maynot always need to be an output of the request indication device. Thefollowing is some examples of the request indication device and thetorque request issued to the transmission:

a signal of requesting acceleration issued by an automatic speed controldevice (cruise control) of the vehicle; or

an output of a switch and volume different from the acceleratoroperator, which is operated by the driver.

The embodiments described above illustrate the example in which thecontrol device configured to receive a signal is provided. Here, thetorque request issued to the transmission is not limited to anelectrical signal. It may be also acceptable that the control device ofthe present invention is operated by, for example, a wire connected toan operation lever. In such a configuration, the supply currentadjustment device may move the stator core by using a force transmittedfrom the wire.

In the embodiments described above, the three-phase brushless motor isillustrated as an example of the motor 18. The motor of the presentinvention may be a motor having the same structure as that of thegenerator described in the embodiments, including the structure of thesupply current adjustment device. For example, like the generator 30,the motor 18 may be structured so as to include the plurality of firststator core parts and the second stator core part and configured to moveone of the first stator core parts and the second stator core partrelative to the other.

In the embodiments described above, the vehicle V having four wheels isillustrated as an example of the apparatus to which the transmission isapplied. Applications of the transmission of the present invention,however, are not limited thereto, and it may be applicable to a vehiclewith three or less wheels, a vehicle with five or more wheels, and avehicle with no wheel.

The transmission of the present invention is applicable to, for example,a vehicle provided with wheels. The transmission of the presentinvention is applicable to, for example, motorcycles, motor tricycles,buses, trucks, golf carts, carts, ATVs (All-Terrain Vehicles), ROVs(Recreational Off-highway Vehicles), and track-type vehicles.

The transmission of the present invention is applicable to, for example,a vehicle in which a drive mechanism different from wheels is driven.The transmission of the present invention is applicable to, for example,industrial vehicles typified by forklifts, snow blowers, agriculturalvehicles, military vehicles, snowmobiles, construction machines, smallplaning boats (water vehicles), marine crafts, outboard engines, inboardengines, airplanes, and helicopters.

The rotational drive mechanism includes a driving member. The rotationaldrive mechanism may be a device, for example, a propeller, an impeller,a caterpillar, or a track belt. The rotating mechanism may notnecessarily be a mechanism that drives a vehicle. The rotating mechanismmay be a mechanism that drives a part of functions provided in avehicle.

The transmission of the present invention is applicable to, for example,engine blowers, snow blowers, lawn mowers, agricultural implements, gasengine heat pumps, and general-purpose machines.

In the embodiments described above, the control device 15 constituted ofa microcontroller is illustrated as an example of the control device.This, however, is not limiting the present invention. The control devicemay be constituted of a wired logic, for example.

The generator of the present invention may not always need to beattached to the crank case of the engine. The transmission of thepresent invention may be arranged in a position distant from the engine.For example, the transmission may configure a vehicle drive transmissiondevice mountable to and dismountable from a vehicle body of a vehicle.Such a vehicle drive transmission device is an apparatus constituted ofa physically single body that is mounted to and dismounted from thevehicle body. The vehicle drive transmission device is configured suchthat all components (for example, a generator, a motor, and the like)included in the vehicle drive transmission device are, as a single body,mountable to and dismountable from the vehicle body.

The torque request is a request for increasing, decreasing, ormaintaining the torque outputted from the transmission to the rotatingmechanism. Thus, a request for causing the torque outputted from thetransmission to the rotating mechanism to rise from zero falls into thetorque request. A request for zeroing the torque outputted from thetransmission to the rotating mechanism falls into the torque request. Arequest for maintaining the torque outputted from the transmission tothe rotating mechanism at zero is substantially equivalent to a requestfor keeping the transmission from outputting a torque to the rotatingmechanism. Therefore, the request for maintaining the torque outputtedfrom the transmission to the rotating mechanism at zero does not fallinto the torque request. In other words, while the torque outputted fromthe transmission to the rotating mechanism is maintained at zero, notorque request is inputted. In the present invention, when the torquerequest is inputted to the transmission, the control device directs thesupply current adjustment device to change the magnetic resistance ofthe magnetic circuit for the winding, which passes through the statorcore. When the torque is outputted from the transmission to the rotatingmechanism, the control device directs the supply current adjustmentdevice to change the magnetic resistance of the magnetic circuit for thewinding, which passes through the stator core, in accordance with thetorque request inputted to the transmission.

The change of the inductance of the winding is implemented by changingthe magnetic resistance of the magnetic circuit for the winding, whichpasses through the stator core. The change of the magnetic resistance ofthe magnetic circuit for the winding, which passes through the statorcore, may be implemented in a plurality of stages or in a single stage,or may be implemented continuously. In other words, the output currentcharacteristics of the generator may be changed in a plurality of stagesor in a single stage, or may be changed continuously.

The broken line H1 of FIG. 9 represents exemplary output currentcharacteristics obtained when the magnetic resistance of the magneticcircuit for the winding, which passes through the stator core, is low.The solid line H2 of FIG. 9 represents exemplary output currentcharacteristics obtained when the magnetic resistance of the magneticcircuit for the winding, which passes through the stator core, is high.That is, the output current characteristics of the generator shown inFIG. 9 are not to be interpreted as limiting the change of the magneticresistance of the magnetic circuit for the winding, which passes throughthe stator core, to a two-stage change as illustrated in thisembodiment. The output current characteristics of the generator may bechanged in a plurality of stages or in a single stage, or may be changedcontinuously. The output current characteristics represented by thebroken line H1 and the solid line H2 of FIG. 9 are contained in theoutput current characteristics that are changed in a plurality ofstages, in a single stage, or continuously. In the present invention,the magnetic resistance of the magnetic circuit for the winding, whichpasses through the stator core, may be changed in two stages.

A situation where the supply current adjustment device changes the stateof the generator from one of a high-resistance state and alow-resistance state to the other will be described. In thelow-resistance state, the magnetic resistance of the magnetic circuitfor the winding, which passes through the stator core, is lower thanthat in the high-resistance state. For example, in a case where thestate of the generator is changed so as to increase the magneticresistance of the magnetic circuit for the winding, which passes throughthe stator core; the state of the generator before the change is thelow-resistance state and the state of the generator after the change isthe high-resistance state. In a case where the state of the generator ischanged so as to reduce the magnetic resistance of the magnetic circuitfor the winding, which passes through the stator core; the state of thegenerator before the change is the high-resistance state and the stateof the generator after the change is the low-resistance state. Thus, noparticular limitation is put on the absolute value of the magneticresistance of the magnetic circuit for the winding, which passes throughthe stator core, in each of the high-resistance state and thelow-resistance state. The high-resistance state and the low-resistancestate are defined in a relative sense. The inductance of the winding inthe high-resistance state is lower than the inductance of the winding inthe low-resistance state.

In an example described below, exemplary output current characteristicsof the generator in the low-resistance state correspond to the brokenline H1 of FIG. 9, and exemplary output current characteristics of thegenerator in the high-resistance state correspond to the solid line H2of FIG. 9. At the rotation speed (M) corresponding to the intersection Mbetween the broken line H1 and the solid line H2, the generator in thehigh-resistance state and the generator in the low-resistance stateoutput an equal magnitude of current at the equal rotation speed (M).That is, output current characteristic curves (H1, H2) of the generatorobtained before and after the change of the magnetic resistance of themagnetic circuit for the winding, which passes through the stator core,have the intersection therebetween, and there is the rotation speed (M)corresponding to this intersection. Here, an output currentcharacteristic curve means a curve representing the output current ofthe generator relative to the rotation speed of the rotor.

As shown in FIG. 9, the generator of the present invention is configuredsuch that, in a case where the supply current adjustment device changesthe state of the generator from the low-resistance state to thehigh-resistance state, the generator in the high-resistance state (H2)is able to output a current (I2) when rotating at a rotation speed (M+)higher than the rotation speed (M), the current (I2) being larger thanthe maximum current that could be outputted by the generator in thelow-resistance state (H1) rotating at the rotation speed (M+). In thegenerator of the present invention, the state of the generator ischanged so as to increase the magnetic resistance of the magneticcircuit for the winding, which passes through the stator core, thusenabling the generator to output a large current that could not beoutputted at a relatively high rotation speed before the change.

As shown in FIG. 9, the generator of the present invention is configuredsuch that, in a case where the supply current adjustment device changesthe state of the generator from the high-resistance state to thelow-resistance state, the generator in the low-resistance state (H1) isable to output a current when rotating at a rotation speed (M−) lowerthan the rotation speed (M), the current being larger than the maximumcurrent that could be outputted by the generator in the high-resistancestate (H2) rotating at the rotation speed (M−). In the generator of thepresent invention, the state of the generator is changed so as to reducethe magnetic resistance of the magnetic circuit for the winding, whichpasses through the stator core, thus enabling the generator to output alarge current that could not be outputted at a relatively low rotationspeed before the change.

As thus far described, the generator of the present invention isconfigured such that the generator after the supply current adjustmentdevice changes the magnetic resistance of the magnetic circuit for thewinding, which passes through the stator core, is able to output acurrent at the rotation speed (M− or M+) higher or lower than therotation speed (M), the current being larger than the maximum currentthat the generator could output at the rotation speed (M− or M+) beforethe change.

The transmission of the present invention is able to supply a rotationaltorque different from the rotational torque outputted from the engineand a rotation speed different from the rotation speed outputted fromthe engine to the rotating mechanism (for example, the rotational drivemechanism).

The control device 15 controls the supply current adjustment device 131as well as the converter 16 and/or the inverter 17 serving as the motorpower control device in accordance with the torque request. In thiscase, the control device may perform a control of changing the operationmode of the motor power control device in accordance with the torquerequest at the same time as or at a different time than when performingthe control of changing the inductance via the supply current adjustmentdevice in accordance with the torque request. Here, the control ofchanging the operation mode of the motor power control device is acontrol of changing an on/off pattern of the converter and/or theinverter from one predefined pattern to another predefined pattern. Thepattern recited herein may be a pattern whose on/off cycle is constant,or may be a pattern whose on/off cycle varies over time. The control ofchanging the operation mode of the motor power control device isdistinct from a control of the operation of the motor power controldevice. The control of the operation of the motor power control deviceis a control for causing the motor power control device to operate basedon a predefined on/off pattern.

It should be understood that the terms and expressions used in theembodiments above are for descriptions and have no intention to beconstrued in a limited manner, do not eliminate any equivalents offeatures shown and mentioned herein, and allow various modificationsfalling within the claimed scope of the present invention. The presentinvention may be embodied in many different forms. The presentdisclosure is to be considered as providing examples of the principlesof the invention. A number of illustrative embodiments are describedherein with the understanding that such examples are not intended tolimit the invention to preferred embodiments described herein and/orillustrated herein. The embodiments described herein are not limiting.The present invention includes any and all embodiments having equivalentelements, modifications, omissions, combinations, adaptations and/oralterations as would be appreciated by those in the art based on thepresent disclosure. The limitations in the claims are to be interpretedbroadly based on the language employed in the claims and not limited toexamples described in the present specification or during theprosecution of the application. The present invention should beinterpreted broadly based on the language employed in the claims.

REFERENCE SIGNS LIST

T transmission

V vehicle

10, 20, 30 generator

11, 21, 31 rotor

12, 22, 32 stator

14 engine

15 control device

16 converter

17 inverter

18 motor

131, 231, 331 supply current adjustment device

141 engine output adjustment device

151 torque request receiving device

152 adjustment control device

323 first stator core part

324 second stator core part

344 supply voltage adjustment device

1. A transmission configured to output a rotational torque in accordancewith a torque requirement, comprising: a generator, including a rotor,including a permanent magnet, configured to receive first rotationalpower from an engine, a stator including a stator core with a windingwound thereon, the first rotational power causing the rotor and thestator to generate a current for outputting by the generator, and asupply current adjustment device configured to adjust magneticresistance of a magnetic circuit for the winding, which passes throughthe stator core, to thereby change an inductance of the winding toadjust the output current; a motor configured to be driven by thecurrent outputted from the generator, to thereby output secondrotational power; and a control device configured to control the supplycurrent adjustment device to change the inductance of the winding, inaccordance with the torque requirement.
 2. The transmission according toclaim 1, further comprising a motor power control device provided in anelectric power supply path between the generator and the motor, whereinthe control device controls both the motor power control device and thesupply current adjustment device, to thereby adjust the current suppliedto the motor.
 3. The transmission according to claim 2, wherein themagnetic circuit for the winding, which passes through the stator core,includes at least one non-magnetic gap between the winding and therotor, and the supply current adjustment device adjusts the current tobe outputted from the generator by changing the inductance of thewinding, which is implemented by changing magnetic resistance of thenon-magnetic gap between the winding and the rotor.
 4. The transmissionaccording to claim 3, wherein the magnetic circuit for the winding,which passes through the stator core, includes at least one non-magneticgap, and the supply current adjustment unit adjusts the current to beoutputted from the generator by changing the inductance of the winding,which is implemented by changing magnetic resistance of a non-magneticgap among the at least one non-magnetic gap, the magnetic resistance ofthe non-magnetic gap being highest when the inductance of the winding isset to a highest settable value.
 5. The transmission according to claim4, wherein the supply current adjustment device changes the magneticresistance of the magnetic circuit for the winding, which passes throughthe stator core, by moving at least a portion of the stator corerelative to the winding, to thereby adjust the current to be outputtedfrom the generator.
 6. The transmission according to claim 3, whereinthe supply current adjustment device changes the magnetic resistance ofthe magnetic circuit for the winding, which passes through the statorcore, by moving at least a portion of the stator core relative to thewinding, to thereby adjust the current to be outputted from thegenerator.
 7. The transmission according to claim 2, wherein themagnetic circuit for the winding, which passes through the stator core,includes at least one non-magnetic gap, and the supply currentadjustment unit adjusts the current to be outputted from the generatorby changing the inductance of the winding, which is implemented bychanging magnetic resistance of a non-magnetic gap among the at leastone non-magnetic gap, the magnetic resistance of the non-magnetic gapbeing highest when the inductance of the winding is set to a highestsettable value.
 8. The transmission according to claim 7, wherein thesupply current adjustment device changes the magnetic resistance of themagnetic circuit for the winding, which passes through the stator core,by moving at least a portion of the stator core relative to the winding,to thereby adjust the current to be outputted from the generator.
 9. Thetransmission according to claim 2, wherein the supply current adjustmentdevice changes the magnetic resistance of the magnetic circuit for thewinding, which passes through the stator core, by moving at least aportion of the stator core relative to the winding, to thereby adjustthe current to be outputted from the generator.
 10. The transmissionaccording to claim 1, wherein the control device is configured tocooperate with the engine to adjust the first rotational power outputtedtherefrom.
 11. The transmission according to claim 10, wherein themagnetic circuit for the winding, which passes through the stator core,includes at least one non-magnetic gap between the winding and therotor, and the supply current adjustment device adjusts the current tobe outputted from the generator by changing the inductance of thewinding, which is implemented by changing magnetic resistance of thenon-magnetic gap between the winding and the rotor.
 12. The transmissionaccording to claim 11, wherein the magnetic circuit for the winding,which passes through the stator core, includes at least one non-magneticgap, and the supply current adjustment unit adjusts the current to beoutputted from the generator by changing the inductance of the winding,which is implemented by changing magnetic resistance of a non-magneticgap among the at least one non-magnetic gap, the magnetic resistance ofthe non-magnetic gap being highest when the inductance of the winding isset to a highest settable value.
 13. The transmission according to claim12, wherein the supply current adjustment device changes the magneticresistance of the magnetic circuit for the winding, which passes throughthe stator core, by moving at least a portion of the stator corerelative to the winding, to thereby adjust the current to be outputtedfrom the generator.
 14. The transmission according to claim 11, whereinthe supply current adjustment device changes the magnetic resistance ofthe magnetic circuit for the winding, which passes through the statorcore, by moving at least a portion of the stator core relative to thewinding, to thereby adjust the current to be outputted from thegenerator.
 15. The transmission according to claim 10, wherein themagnetic circuit for the winding, which passes through the stator core,includes at least one non-magnetic gap, and the supply currentadjustment unit adjusts the current to be outputted from the generatorby changing the inductance of the winding, which is implemented bychanging magnetic resistance of a non-magnetic gap among the at leastone non-magnetic gap, the magnetic resistance of the non-magnetic gapbeing highest when the inductance of the winding is set to a highestsettable value.
 16. The transmission according to claim 15, wherein thesupply current adjustment device changes the magnetic resistance of themagnetic circuit for the winding, which passes through the stator core,by moving at least a portion of the stator core relative to the winding,to thereby adjust the current to be outputted from the generator. 17.The transmission according to claim 10, wherein the supply currentadjustment device changes the magnetic resistance of the magneticcircuit for the winding, which passes through the stator core, by movingat least a portion of the stator core relative to the winding, tothereby adjust the current to be outputted from the generator.
 18. Thetransmission according to claim 1, wherein the magnetic circuit for thewinding, which passes through the stator core, includes at least onenon-magnetic gap between the winding and the rotor, and the supplycurrent adjustment device adjusts the current to be outputted from thegenerator by changing the inductance of the winding, which isimplemented by changing magnetic resistance of the non-magnetic gapbetween the winding and the rotor.
 19. The transmission according toclaim 18, wherein the magnetic circuit for the winding, which passesthrough the stator core, includes at least one non-magnetic gap, and thesupply current adjustment unit adjusts the current to be outputted fromthe generator by changing the inductance of the winding, which isimplemented by changing magnetic resistance of a non-magnetic gap amongthe at least one non-magnetic gap, the magnetic resistance of thenon-magnetic gap being highest when the inductance of the winding is setto a highest settable value.
 20. The transmission according to claim 19,wherein the supply current adjustment device changes the magneticresistance of the magnetic circuit for the winding, which passes throughthe stator core, by moving at least a portion of the stator corerelative to the winding, to thereby adjust the current to be outputtedfrom the generator.
 21. The transmission according to claim 18, whereinthe supply current adjustment device changes the magnetic resistance ofthe magnetic circuit for the winding, which passes through the statorcore, by moving at least a portion of the stator core relative to thewinding, to thereby adjust the current to be outputted from thegenerator.
 22. The transmission according to claim 1, wherein themagnetic circuit for the winding, which passes through the stator core,includes at least one non-magnetic gap, and the supply currentadjustment unit adjusts the current to be outputted from the generatorby changing the inductance of the winding, which is implemented bychanging magnetic resistance of a non-magnetic gap among the at leastone non-magnetic gap, the magnetic resistance of the non-magnetic gapbeing highest when the inductance of the winding is set to a highestsettable value.
 23. The transmission according to claim 22, wherein thesupply current adjustment device changes the magnetic resistance of themagnetic circuit for the winding, which passes through the stator core,by moving at least a portion of the stator core relative to the winding,to thereby adjust the current to be outputted from the generator. 24.The transmission according to claim 1, wherein a magnetic flux forms inthe rotor and is linked with the winding, the magnetic flux changing, ata first change rate, as the rotor rotates, and the supply currentadjustment device adjusts the current to be outputted from the generatorby changing the inductance of the winding at a second change rate thatis higher than the first change rate.
 25. The transmission according toclaim 1, wherein the supply current adjustment device changes themagnetic resistance of the magnetic circuit for the winding, whichpasses through the stator core, by moving at least a portion of thestator core relative to the winding, to thereby adjust the current to beoutputted from the generator.
 26. The transmission according to claim25, wherein the supply current adjustment device causes the portion ofthe stator core to move relative to the winding while maintaining aposition of the stator core relative to the rotor.
 27. The transmissionaccording to claim 1, wherein the supply current adjustment devicechanges the magnetic resistance of the magnetic circuit for the winding,which passes through the stator core, by moving the winding, to therebyadjust the current to be outputted from the generator.
 28. Thetransmission according to claim 1, wherein a linkage flux flows from thepermanent magnet of the rotor and is linked with the winding; and thegenerator further includes a supply voltage configured to change thelinkage flux to thereby change an induced voltage of the winding toadjust a voltage outputted from the generator.
 29. The transmissionaccording to claim 28, wherein the supply voltage adjustment devicechanges the linkage flux by moving the permanent magnet relative to thewinding.
 30. The transmission according to 28, wherein the supplyvoltage adjustment device includes a voltage supply adjustment mechanismconfigured to change the linkage flux flowing from the permanent magnetof the rotor and linked with the winding by moving the rotor, to therebychange the induced voltage of the winding to adjust the supply voltage.31. The transmission according to claim 30, wherein the supply voltageadjustment device further includes a voltage adjustment control device,which is one of a circuit, and a processor executing programinstructions, configured to control the voltage supply adjustmentmechanism to move the rotor in accordance with the torque requirement.32. The transmission according to claim 1, wherein the stator coreincludes a plurality of first stator core parts, each having a facingportion that is opposite to the rotor with a non-magnetic gaptherebetween, and a second stator core part, and the supply currentadjustment device changes the magnetic resistance of the magneticcircuit for the winding, which passes through the stator core, by movingone, relative to the other, of the plurality of first stator core partsand the second stator core part.
 33. The transmission according to claim32, wherein the move of the one of the plurality of first stator coreparts and the second stator core part relative to the other causes astate of the stator to shift from a first state in which a width of anon-magnetic gap between each of the plurality of first stator coreparts and the second stator core part is smaller than a width of anon-magnetic gap between adjacent ones of the plurality of first statorcore parts to a second state in which the width of the non-magnetic gapbetween each of the plurality of first stator core parts and the secondstator core part is larger than the width of the non-magnetic gapbetween adjacent ones of the plurality of first stator core parts. 34.The transmission according to claim 1, wherein the control deviceincludes one of a circuit and a processor executing programinstructions, configured to control the engine to adjust the outputrotational power and to control the supply current adjustment device toadjust the inductance of the winding.
 35. A vehicle comprising: thetransmission according to claim 1; the engine; and a rotational drivedevice that receives the rotational torque from the transmission.
 36. Acontrol device for use in a transmission having a generator, including arotor, including a permanent magnet, configured to receive rotationalpower from an engine, a stator including a stator core with a windingwound thereon, a magnetic circuit for the winding passing through thestator core, the rotational power causing the rotor and the stator togenerate a current for outputting by the generator, and a supply currentadjustment device configured to adjust magnetic resistance of themagnetic circuit for the winding, to thereby change an inductance of thewinding to adjust the output current, and a motor configured to bedriven by the current outputted from the generator, to thereby output arotational torque in accordance with a torque requirement, the controldevice comprising: one of a circuit and a processor executing programinstructions, configured to receive the torque requirement, and controlthe supply current adjustment device to change the inductance of thewinding, in accordance with the received torque requirement.